All well and good until you start taking shots from multiple angles. Distributed guns and armored sections would improve survival. Why would you line up with the other fleet just to make them happy? You encircle their fleet and hit their unarmed side if it's designed like that, keeping the ships their facing at logner range, shift as they try to react.
The asymmetric ships maneuver, too, and there is no automatic reason that they are less maneuverable than the symmetric ships. Unless the symmetric ships are much more maneuverable than the asymmetric ships, or detection ranges are really short, attempting an englobement invites defeat in detail, if the asymmetric ships can engage part of the symmetric force before the disparate elements are close enough to support each other.
Your assumption that the symmetric ships are maneuverable enough to open the range faster than the asymmetric ship can roll seems a tad optimistic.
In the BTU, unlike the sort of milieu I had in mind when describing the great sheets of incandescent radiating surfaces, the only way to figure out where the asymmetric ships's guns are pointing, if it isn't shooting, is to get close enough to read the "This side towards enemy" decal.
As to why to I would line up my ships into a parallel formation when facing such a group of vessels? Because, if they are trying to keep me from shooting their radiators out, I probably want to keep them from doing the same thing to me, and both forces have the detection ranges and maneuverability to keep one from crossing the other's 'T'. In a universe where heat rejection is by radiators, and you cannot shoot through your own radiators, symmetrically armed ships make less sense, especially if their radiators are also symmetric.
By the way, that is an artifact left over from Leviathan... which had a much simpler arc system than the convoluted weapon arcs we have today. They were also a good deal larger than the ships we have in Battletech... so it made sense to a minor degree there... but there at least the anti-fighter and anti-missile guns were turreted. Much simpler game though.
Here, I can not see anything that prevents honestly the turreted main battery. Give it a massive weight penalty, 50% of the mass of the bay... since it is covering now a large number of arcs. I wouldn't mind if it meant I could centralize my guns and know that I can actually fire them at an enemy instead of looking at a massive sheet of weapons, 50% to 60% which may never fire a shot in anger at another warship in the life span of the ship.
I love Leviathan to death. I would still kill to take an Illustris or Shiva out for a spin again... even if both are far too big to be battletech warships. BTW: only Mars, Ultor, and Repulse are reproducible in any way with our current rules. But this was a game that had 1.2 million ton frigates (Hipper & Indomitable) and destroyers (Moltke) that were somehow inferior to the 1.2 million ton cruisers (Invictus) so a good deal of things did not make sense there either.
The reason the Moltke was inferior to the Invictus was that the Moltke had a single huge engine that massed more than half a million tons, but the three engines of the Invictus, due to the non-linear rate mass rose with power output, probably only massed a third of that, despite having upwards of 50% more power than the Moltke.
The construction rules in Leviathan were brutally broken and even I would insist on only using canon units-- a cruiser with 100,000 power units of engines cannot survive any length of time under the guns of a battleships with 101,000 power units of engines, Cruisers of 76,000 power rating trounce 75,000 rated frigates, and 51,000 rated frigates abuse 50,000 rated destroyers. It is still great to play.