Pushing rocks around is fine and dandy, but it would be really cool to see stations or ships anchored to them on the same grid!
This would be an easy feature to add alongside docking and detaching ships, as it would likely share code elements - but it could be added before then as pre-built pirate and neutral stations. Flanking around immobile fortresses or digging through the back side with mining lasers would be a fun puzzle! Maybe you could even see asteroid haulers/pushers as neutral ships flying by.
Unlocking the tech to do it yourself (whenever docking is added) would also be a nice toy to have for late game when the free armor value isn't totally busted.