Specifically ability use.
Autocast is unusable on nearly everything, I'm assuming it sucks now because it's a new release and you haven't gotten much work done on it yet, but it is awfully bad so I'm posting anyway.
TEC lose significant performance on autocast, and a few things like the upgrades for hoshinko and cielo and the level 6 ability for the Akkan get you killed. For the Vasari, they are much more inconvenient.
The missile frigates stop moving in the middle of a move command to get splash damage against units they weren't actually fighting to start with.
The line ships shut down for repairs in midcombat, often near full strength, ignoring the enemy and basically committing suicide against an actual threat.
The carrier repair ability will autocast continually, regardless of a complete lack of anything to repair, it runs the anti-matter down before the shields drop nearly every time.
Suicide by ability is general practice for the meat of the army as opposed to the sole domain of the cielo and hoshinko using secondary abilities.