Not much would be fitted with very same weapons, but that is the point why you should plate it with armors, rather than avoid to. Because, it means the enemy have to spend the most efficient weapons to hunt down them. And those which have good odds againsts VTOL are also usually effective against ASFs. And consider cheap cost of those VTOLs, forcing your opponent to put those specialized weapons or have to waste far more firepower is already enough. That's the advantage you may enjoy because it's NOT a duel, but the group versus group.
An another point is, since it's NOT a duel, why you think about the next turn? If the VTOL loses too much MP thrn even if it does not reduced to 0/0 and got crashed immediately it's not going to survive the next turn, indeed. But is it really meaningful? That would be critical if it's a duel. If it is only a duel, nothing more. But group versus group is different - remember that a downed unit does not immediately results your defeat. Their durability is important because it's NOT a duel, for you will be expected to face the numbers of enemy units, some countermeasures included, also while the enemy can focusing the fire you can do that as well and you do have more than only a VTOL too. If the opponent aims their all the LB-X assets to only one or two VTOLs you have? Congratulation, the other VTOLs and ASFs with anti armor weapon proof you have are all safe this turn, and perhaps those targeted VTOLs are may survives. If they don't got crashed, perhaps they lure the standard anti armor weapons thus buying even an another round as well. Even if they are fallen this round, or the next round, only a handful of 30 tonner, or 60 tonner in the case of superheavy VTOL, would be got the concentrated fire and leaves the other VTOLs or even more of yours unharmed.
If it were a duel or only a handful of units are got involved, indeed it would be a grave loss, but in this case you expect lesser fatality too, and it also means each time the opponent aims your cheap VTOL they bears more risk to waste their precious firepower that have considerable portion on their entire forces. And the durability is even more important on the larger conflict.
All the point is valid as long as the VTOL have good armor point. Otherwise, those would be explodes, and you don't have any chance to complain about a destroyed rotor. Yes VTOLs never bogged downed and keep fights, just crashes, but your idea don't even give them a chance to crash and they are all expected to be explodes on air and you don't have a reason to prepare for a crash. Moreover, while the VTOLs with reasonable armor are only susceptible to LB-X and some cluster weapons and forcing the opponent to bring their anti VTOL assets, the only thing VTOLs with pathetic armor can rely is its good to hit modifier to anyone aims it thanks to its speed, means apart the accracy issue any anti armor weapons will ends them quickly so more enemy units can react to them at ease.
Remember, nothing is invincible, ever, but how hard to silence it does matters. Because the difficulty often results the odds of the engagements.
I think we're talking past each other in some aspects here.
I outlined why I don't use "SLOW" VTOLs-they're a quick kill for the other side in most of the non-duel fights, because non-duellist players will exploit targets that are easy to cripple or kill.
It's a psychology thing, PPLP, which is why the numbers game only tells a fraction of the story. Battles are often won or lost not on the raw calculations, but on exploiting an opponent's mistakes, and taking slow VTOLs instead of something (almost ANYTHING) else? is in my view, a
mistake that will be exploited.as I've said before (many times) it takes mutual cooperation from both sides and optimized team layouts to make slow VTOLs more than a handicap-even with the friendliest optional rules.
In other words, your opponent has to either make lots of mistakes, or intentionally assist your forces for something like a Yellowjacket or Yasha to be an
asset-most of the forces you'd build to make them viable, are actually
better off using something else, and the maps they're favored for by (for example) DevianID's scenario rules?
You're still better off sinking that BV and materiel into something NOT a VTOL, and it's all down to
how VTOL units Operate-both in terms of their unique traits and virtues, and their specific weaknesses. some design ideas just
don't work. They're 'rules legal' and at first blush,doing a number-crunch comparison, they look fantastic-but they
aren't against live opponents whom aren't either intentionally nerfing, or inexperienced/incompetent.
IOW it comes down to where those virtues (the movement abilities in particular) are actually valuable-theyr'e not valuable in a small map, because a small map doesn't actually have enough room to use them. It's like trying to use Aerofighters in a cavern.
The 'virtues' of the VTOL class are movement-you're above the terrain unless you fly low, you get a small bonus on your base to-hit defense modifier, and you can see over obstacles in double-blind play, and there's the rotor hit nerf, which gives a sort of 'limited invulnerability' where you're essentially going to shed 90% of a hit's damage on 30% of your locations for the loss of 1 MP cruising minimum.
To play that game, you need a deep enough cruise MP that you're still viable as a combatant right up to when you fall out of the sky.
To add to that, VTOLs have the best payload-to-speed ratio of any unit in Battletech-the suspension factor means you can carry some nearly absurd loadouts on a very small engine-the payload to speed ratio is fan-frikking-tastic.
But then, you've got the downsides;
Parking is suicide, losing your motive system is fatal, you take falling damage when you go down and that, in turn, can be fatal to characters you're trying to level up. 'Stopped' (no movement or very, very, very slow movement) isn't a viable move, and you can become fatally one with the terrain on a bad PSR if you're trying to get clever and use terrain to get close enough to use short range weapons.
Specifically, if you're flanking to get into position for that good shot.
That means as a player, you're looking at an entire
classification of units where armor protection levels aren't as important as speed. VTOL tactics work with Hovertanks, light 'mechs, WiGEs and quick wheeled vehicles. But tactics that work with those others? don't necessarily ALSO work for VTOLs.
Building a VTOL like an Assault tank? and all you get is a cheap target for the other side and wasted BV, it's not a powerful asset, it's a handicap that must rely on other units to protect it so you can use that overwhelming firepower, and for the budget in tonnage and build, you're better off building (or buying) either an actual assault vehicle, (track, wheel or hover) or sinking that point value into skills for the units you were GOING to use as bodyguards-they'll be more effective.
In turn, PPLP, that means looking at what a VTOL is USEFUL for-it's useful for fast harassment both at range, and up close, there's a below-minimum on armor, sure-the Cyrano's a dog because it's essentially going to be cored by a medium laser hit to the side and is practically the platonic vision of glass hammers.
But the Slow/Armor VTOLs are just as bad with fewer roles where they're actually useful, and no situation where picking literally anything else isn't a better option.
Roles, PPLP. The reason you choose units, is to accomplish things. With any conventional vehicle, the role is also informed by 'we can't afford a proper battlemech for this job'-something that can go slow, lose sections, and still keep fighting.
in that context, there are several canon designs that are flat out BETTER. Even in the 'tough mobile sniper role', but they're better at it either because they're not VTOLs, or because they're fast enough to BE useful for long enough to actually influence the battle.
Hawk Moth, Donar, you get the picture? They can move fast enough to GET in good positions, and get out of trouble before trouble gets into them.
The ability to get the guns on target without needing to flank every turn is USEFUL, the ability to handle a crash landing or lucky hit? is convenient, but it's not completely vital as long as you can handle a 1-3 level drop and still have your pilot alive enough to be rescued.
There are designs that are, in fact, too light...and their BV reflects this, but 'too light' isn't the same as 'ineffectual in the right hands' or 'needs the entire force on both sides configured to make them useful'.