Jick, before you ask U2 to turn into a singles-only band, please ask yourself what happened to those artists who were mainly singles artists during U2's heyday in the late 80s/early 90s.
One example would be George Michael. He put out incredible singles back then, yet the albums could not quite keep up the quality of the singles and it has always taken him long, long periods of time between releases.
Another artist focussed mainly on singles, which I have followed, but who is not from that era, is Mousse T. He tried to put out albums, too, but only one was somewhat of a success. After his last single to date flopped in around 09 because people deemed it too Gaga-ish, he went back to DJing almost fulltime.
Basically, album artists have more staying power than singles artists. I'm afraid U2 would lose their staying power if they were to become a singles-only artist. They might not be heard from after the next 2 singles. And that would be a realshame since they have got so much more geat new music in them, even though not all of it night be considered commercial anymore by the labelheads unlike in the old days.
But in the old days they did not give in when somebody said their songs were not commercial and released them anyway. However, they streamlined the NLOTH album probably because of that. And it shows.