Ehh, the death animations are all used. They just depend on what kind of weapon infantry is killed with. High-explosives (rocket launcher, guard tower machine gun) give the splatter one, tank cannons give the blown away one, flame weapons give the burning one, and light weapons give the falling down one.
The hand-to-hand combat wasn't just removed, it was never really implemented, from what I can see inside the engine.
The reason why should be obvious... don't bring a knife to a gunfight. Further proof of this: