Warships are cool and good, and that's the biggest part I disagree with of your post. Granted, I think Warships should be common enough that they're not campaign-level assets, and further that conducting orbital bombardment where reliable accuracy can be measured in "merely" multiple mapsheets of drift should make a given Warship hideously vulnerable even to ground fire. Make them the 'Mech or tank to the Aerospace fighter's PBI in space, but only in space.
I'm not saying its impossible to ever come up with a set of rules for BT Warships that would be better than what we currently have. But the games focus is ground combat, and I think we can agree the overwhelming majority of Battletech games played are completely ground focused. So, if aerospace rules are going to exist, the parts that
need to be there are those that most connected to ground combat: aerospace fighters and transport dropships.
Theres some even arguments that can be made that the very existence of warships makes ground combat seem irrelevant. (And if they don't, why would you build them given their cost and demand on scare resources)? Even with the generous failing to disregard realism, in Battletech technology, eventually the idea of Warships that can target each other at space ranges, but struggle to hit even the general area of a battlefield from uncontested orbit becomes a bit hard to swallow. And if we make Warships, in setting, so rare that this isnt a factor, then why bother with rules for them in the first place.
In the end, it comes down to being worth the trouble. Sadly, there is only so much 'skull sweat' Catalyst has available, only so many resources to allocate. The business case for a creating a quality working detailed rules set for Warships and assault dropships just doesn't seem to exist.
It comes down to capability, resources, the needs of the game/setting, and at the end, what bang for Catalysts buck spent will they get. Dropships to get mechs to the plant are essential. Hard to have mech combat without a way to get mechs on the planet. Fighter craft are a logical second from that in necessity of needed military units. And if that is all a rules redesign team had to worry about, their burden would be greatly reduced. Beyond that, everything else could be written out, completely, with no great harm to the setting or gameplay, and likely not make a noticeable difference in Catalyst's current bottom line.
And starting form that point of easier goals, maybe they could make a faster, easier, more fun aerospace rules set that would easily integrate with Battletech and Alpha Strike. Maybe more players would invest in a few aerospace fighters. And then, as use across the playerbase increased, the Warship/assault dropship could come back again, with a far more compelling argument for their place.