Yes, this all has been suggested before.
The main problem is that at the speeds in this game, a ton of matter probably has way more punch than a strength 100 warhead, IF there was momentum.
As the technobabble goes for "Space-Time Bending Warp generators" in that respect, the missiles don't actually have any speed, and as such, this wouldn't happen.
What would be possible would be an armor penetrating missile, sort of like a HEAT charge, that deals less damage and has a lower to hit chance in turn for higher armor penetration.