I don't think any of those are unneeded.
Troops: simultanious combat, same as with ships. The design of a troop makes a difference. Cheap riot-control troops, heavily armored main line troops, heavily -armed- backup troops, etc. To say nothing of what it lets you do in terms of moddng.
Same with fighters and sats. In one game I currently have 7 different types of fighter active. Ship attack, interceptor, fast ship attack, fast interceptor, smaller Versions of same (they build faster). Sats: missile sat, sensor sat, ripper beam sat. One or two generics just doesn't cut it. Again the modding posibilities as well.
Mounts: see modding possibilities AGAIN. Especially with the new Gold patch that allows different things with then, solved a lot of problems for me.
In the standard game, they're OK if a bit overpowered. But then I don't see you suggesting removing the PPB from the game because it's overpowered..
Phoenix-D