Player housing is fun for the same reason people like The Sims or Sim City or whatever else. its fun to work to build something of your own that you have to overcome certain hurdles to design.
I honestly didn't like rift that much. Its an ok game, but every feature I feel like I've done for 5 years already in WoW, so it didn't interest me. However with Rift introducing player housing, this one thing really makes me want to give it another shot.