I don't understand why people keep thinking Magnificent would've done so much better than Boots. Look at U2's popularity in todays' mainstream from the past two albums. The lead singles are the most popular ones, Beautiful Day and Vertigo. Both are uptempo rockers. Magnificent is too much a slow song to 'hit' it for a first single, it COULD've been a great 2nd single had the promotion not been shit and if it'd have been a better time. I love how a bunch of you Boots haters were SO convinced magnificent would totally go awesome in the charts. And now it failed you guys still manage to blame it on Boots? Pretty sad if you ask me.
Of course, we'll never know so we're just speculating. I do think that 'Magnificent' would have done a bit better business if it had come out before the album, since it's so much more tuneful and radio-friendly than 'Boots'. Having said that, I don't think it (or any song on NLOTH) could have been a big hit.
But the fact that 'Magnificent' failed to set the world on fire as a 2nd single does not mean that it wouldn't have changed the general perception of NLOTH -- it might have. The casual fans of U2 (who outnumber us on this forum by about 1000 to 1) take a lot of their cue from the first single. Look at how many threads today are still discussing U2's dressing up like the Village People in 1997! That first release/video/download/whatever sets a lot of the tone for the campaign that follows.
I do think that public in general is a bit tired of U2 at the moment, as they were in 1997. Of course they're going to sell-out concerts because who doesn't want to go and see them live rather than stay home for an evening? But as far as records/hits/singles go, I feel that anything U2-ish right now ('Magnificent' being the most U2-ish song on the album) is not going to excite people.
I actually blame the group for this. I think they were far too over-exposed in the interim between HTDAAB and NLOTH. Yes, there was a really long gap between records (which may have hurt them in another way), but in the meantime there were countless DVDs, re-issues, TV appearances, etc., etc. Sometimes, if you're going to take some time out, it's better to really disappear for a while and let people miss you. (That's kind of what happened in 1989 to 1991, for example -- well, in N. America anyway.)