First off, there is nothing wrong with a band wanting to make money and be in the charts. Any band that tells you they want neither is bullshitting you.
Once again, I refer back to this wonderful interview with Bono from earlier this year:
http://www.interference.com/u2128132/index.html
Second, knowing that shooting for money or the charts in the midst of making music is not evil, please don't think that this is somehow magically new to post-90s U2:
1. From the day they signed Paul McGuinness, the U2 organization has been carefully and decisively run in all matters, both business-wise and musically.
2. All four members have said at one time or another that when they formed the band 29 years ago, they formed it with the punk goal of taking down "mainstream music" by getting on the mainstream charts.
3. Read any story on the creation of JT that mentions the millions of B-sides & unreleased songs from that era and you will find that they were looking for singles even then. Sure, they were also looking for theme--but there are themes to these last two albums, as well (and if you don't see them, you're not looking).
4. U2 were ecstatic when they finally got their first #1 US single via JT. They were also ecstatic to be on the cover of Time.
5. For all the artsiness and experimentation of the 90s, U2 were still very business-oriented. The Flanagan book
clearly outlines and foreshadows U2's iPod deal, ten years early, describing how U2 recognized the importance of owning/partnering with the best hardware that would play their software (their music). If you believe in "selling out," then U2 were thinking about it even in the midst of their "anti-sell-out"/experimental phase.
This money thing is not new. And it's not bad or wrong. Bands that talk about "selling out" are lame-ass bands that simply haven't made it yet.
As for the "mainstream" debate, I know several people who listened to ATYCLB and HDAAB and said that there were only one or two songs on each that were radio-worthy. Lo and behold, there are several from each. These albums are only slightly more mainstream than JT was in the 80s (in the wake of Madonna, Michael Jackson, and other crap), and much less so than Boy or War were in their day. The reason so many of their songs get on the radio and
become mainstream is because it's U2, and they make good music that sticks with people and defines its own corner of mainstream. That's one of the many, many things that makes U2 great.