I don't think it's U2 changing that people have a problem with, but it's their explicit admission that they are once again trying to be popular and accepted by the most people possible.
That, coupled with a simultaneous decrease in the quality of Bono's songwriting, have occasioned more disillusionment with U2 that there mere fact that they changed their style.
U2 wanting to be popular and accepted is really not new, is it ?
Of course not, but there's a difference between writing challenging new music and embracing it so wholeheartedly that you play almost your whole album live, and rarely break character for three years, thereby almost dragging an unwilling audience along for the ride with you (on the one hand), and deliberately doing everything you can to be likeable and tame (on the other).
No one here thinks U2 didn't care about success in the '90s. It's just that they also cared about other things.
If you're referring to Zoo era (character for three years, playing full album), they had at least two things going for them : a) massive groundbreaking tour. With that tour U2 became a stadium act, a must-see live band. The tour itself was the selling prize, not so much the - admiteddly excellent - album. b) not one, but two massive US hits in MW and One. And they were out of US live dates for what...5 years since JT tour ? Demand was pretty much a given.
Same band that wanted to fight the charts in 83. Same band that shouted off about it each night on JT tour (we worked hard to be no 1 speeches). But they always had the songs to back it up. Same band that wrote BD and had the brilliant idea for the Ipod hookup (though as far as I'm concerned, Vertigo would have been a hit with or without the ad). Except this band doesn't have the luxury of automatic radio airplay or MTV. 50 year old pack of rockers in American music landscape ... Vertigo and BD were a miracle IMO. Anything similarly big is wishful thinking on their part IMO.
I don't think they ever sold out "art" for the sake of "commerce". I concede that as they get better at the "craft" of writing some of the "magic" might get lost but that is a different debate. I'm not concerned about their integrity when they can still pull of pure inspiration like Moment of surrender.