When playing, I always use wasd to move around, and conviently, w/up in that mode can open menus when talking to pigs etc. What I want is for spacebar to work as enter, so I can use that to select "feed" etc.
I personally have an issue with my right hand; it's got a little carpal tunnel action going on that my left hand doesn't. While I don't mind typing as much, just sitting there to hit enter all the time starts to really really agrivate it. So if I could instead hit the spacebar with my left hand which is already over wasd, that'd be a huge pain savings for me :)