I think Mike hit the nail on the head. They play to please the crowd. That's why songs like "Bad Name" and "Bad Medicine" and "Sleep When I'm Dead" will forever be in the set list. If you pay attention to the crowd reactions, those are the songs that get people going. I make no secret that I'd be the happiest girl in the world if they never played Bad Name live again. I could live without Wanted, Bad Medicine, Sleep, Prayer, Lay Your Hands On Me, and all the other staples of the show, but that's because I've been to a few shows and have hundreds of shows on audio/video. It's not new to me anymore. To the majority of the people in the arena or stadium, the live experience is a new one or a rarely experienced one. When we go to Atlanta, if they don't do those songs that Julie hasn't seen live since 1989, she will leave very disappointed. There are a lot more Julies out there than Beckys!
Jon mentioned before the Crush tour that the song HE most wanted to play was "Mystery Train" and it was in the set lists at first. He later said that it wasn't going over very well, so it got cut out as a regular.

The band aims to put on the best show possible and to the majority of the concert-goers that means the old standbys that casual fans go to hear. If you were a casual Bon Jovi fan who went to see them and they left out the hits, you'd be very disappointed when you left. The band wants people to be happy when they left, not bitching because they didn't do the songs the fans came to hear.
The fans like us who know every word to every song (and every demo) the band has ever released and lot that they haven't released are very much in the minority.
And, about Dave and drum loops... has anyone considered that he's using technology to help him due to his finger injury which he has said still causes him great pain at times?
Becky