Feature proposals/Ragdoll death animations
Currently, death animations must be created by hand by an animator, which is a time consuming process. As such, the number of death animations is finite and typically very little. A death animation that would otherwise stand on its own might look terrible in certain gameplay contexts, as well; for example, an animation of a human falling to the floor that they are standing on looks awful when played as said character is falling through space.
Specific behaviors
Trapper
The trapper (and likely other alien structures, in future) poses an interesting problem in that it remains attached to the ceiling when it dies, but one would expect its tail to fall down and flop about realistically. As it stands now, the death animation only looks correct when it is built on the floor. A simple Newtonian particle physics system with springs should do to procedurally calculate positions of the tail bones.