All of the above is true. I didn't mean that a singles chart position shouldn't be of importance to you or I, that's all about pride in your favourite band and thats great. I just meant that singles sales have dropped off (in Australia at least) at such a staggering rate, that their promotion is barely worth the cost. Just have a look at the space the 'singles section' of your local record store now commands compared to even 5 years ago, let alone 10 years ago. I don't know the current stats, I don't work in the music industry anymore, but as of 2002, the amount of sales you needed to reach #1 was only 50% of what you needed in 2000. That's 2 years difference and downloading has made far more inroads since then. I would guess it would be around 20-25% now, maybe less. There will be the occasional mass seller (debut Australian Idol single for example) but it's very rare and an average weeks number 1 would have been a number 20 ten years ago.
Not only that but the singles buying market has narrowed completely. It is now pretty much only teenagers and kids, more specificaly teenage girls, who buy singles regularly. This is certainly not U2's market. So when I say "singles are not important" I'm not referring to individual songs popularity as not being important, I'm just saying that the singles market is on such a fast downward slide, I'd be genuinely surprised if they exist at all in 2-3 years. As this is occuring, due to it being a 'dead market', record companies are only sinking money into it if it's a product that can still do good business there. The ones you mention above, Destinys Child, Missy Higgins etc appeal to the singles market, their singles will be heavily promoted. U2's market know the band well. If they hear a couple of songs they like, they'll buy the album. They won't buy singles. They know U2 are better than one song alone.