I agree that the battle-space could use more variation in obstacles. If nothing else, some variant AsteroidAPIs. If that was moddable at all, I'd have made a bunch of new asteroids, lol.
The issue with the dead ships has always been straightforward; the collision checks and other things going on with the ship chunks eat CPU like there's no tomorrow. It was bad enough with Hulks; it's worse with the broken-up bits. Sure, it looks cool, but in massive battles, it's a serious problem.
It's just not very cheap to do collision checks with these things (although there are probably some speedups possible here and there). If they take damage, it's a big deal to update them (this could probably get cheaper, but IDK; they appear to be conventional ShipAPIs, basically, which suggests yes).
Honestly, for anything but the largest ships, it might work better to use generic bitz; asteroids aren't "free", but they're quite cheap, comparatively, because they can use a simpler collision system and damage system.