I think there are many reasons why house shows are better.
For one, there's more action. You don't have to sit thru all the stupid video packages and go thru all the stuff that happens during commercial breaks. It really is just a wrestling show.
Also, from my experience, the show seems more personalized to the local crowd. On TV they're more worried about playing to the worldwide audience. In house shows, the wrestlers seem to interact with the fans more.
Whenever I watch a house show, I'm reminded and amazed at how many times a year these guys go thru this. Its a rough, circus schedule. I get nitpicky a lot, and justifiably so, but I can't deny that most of these guys do work their butts off (usually my real beef is with the bookers). And often times they'll come up with something creative just for the local crowd. You'll see stuff that you'd never see on TV.