Ships should be able to collide with each other, whether on purpose or by accident. I used the Kamakazi tactics in Homeworld all fo the time back in the day. Plus it would be cool if there was a capital ship that had the ability to self-destruct and cause massive splash damage (make it a level 6 ability, so you'll think twice before sacrificing a valuable ship). If this does become an ability, I would just ask the devs to not make it auto-cast.