Personally I think it depends on whether or not your piggies will find a loft enjoyable/enriching. Mine love their loft. Shadow wouldn't go up there for weeks but suddenly decided it wasn't scary after all and now both of them spend most of their time there! It's also a 3x1 loft. However you do have enough floor space without.
My pigs quite like zooming up and down the ramp, but definitely prefer having their food within stretching distance
Some pigs will never use a ramp, it all depends on your piggies. I had a 2x2 loft on a 3x5 cage and cleaning was a nightmare. They seem to zoom around and popcorn more without the loft though.
My piggies loft has a ramp on either end and Sunrise sometimes runs mad circuits up one, across, down the other and back to the beginning. tee hee. My other pig Shadow watches and occasionally popcorns when she zooms past. May I ask Nat453 why having a loft made cleaning a pain?
@Nessy - I recently broke my foot and I'm in a cast so getting right in the corner was a pain. Apart from that it kept the hay mess in one area (yay!) and the majority of poops were only in one other corner. I'll probably put mine back on after I get this stupid cast off though
if you have the space, i would say the loft really isn't necessary. for me i feel it's neater as it keeps the hay off the main floor and i change the fleece+towels more frequently there, allowing the main floor to require less frequent changing.