popacrobat, i believe GOYB was seen by u2 as the most 'safe' of the NLOTH songs, hence why it was chosen as lead single, but the tactic did not work. To me, the song is emulating vertigo, which obviously was really successful, so the band felt it was most wise to have Boots representing the album. Ironically, this failed, and i presume it failed because not enough people thought the song was good, therefore affecting single and album sales.
This was because they thought they were being safe by making a song similar to vertigo, when the song just needed to be good... the best analogy i can think of is bringing a parachute with you when you go scuba diving. u2 were focusing on the wrong 'safety precautions' while aiming for sales. All they needed to be safe was to have a good song, not a clever, unusual, or copycat one.
Same goes for the other two singles - both 'safer' (more accessible) than say, Moment of Surrender. however, i think MOS is a better song, and therefore i think it would have sold better.
I'm sure u2 are smart enough to know that they can't just copy their previous lead singles, or be 'safe' for success, otherwise they'd release a GOYB type song again, and it would fail again.
This is all really good, because i think u2's aim with the next album is not to have success by making 'safe', 'back to basics' songs, or 'experimental, head-scratching' songs, but simply good songs. I think u2 have realised with NLOTH that they can't allow their future track list to be determined by how 'by the books' or novel the music is, but just how good the tune is.
It means whatever we get, stripped back or experimental, hey, it's u2, it's gonna rock