There's a big difference between constructive criticism for the band that comes from a place of fondness and faithfulness, and the type of nasty, negative backbiting where someone turns on U2 as soon as the band does something that doesn't meet their particular expectations.
What's missing from so many of these critical comments is any sense of faithfulness. When U2 does what we like, we're happy, and when U2 doesn't, we turn on them and tear them to pieces.
True faithfulness is characterized by continuing to love something even when things don't turn out exactly the way you hoped (which is different than blindly praising everything). Unfaithfulness is characterized by a "I can take it or leave it" type of mentality that doesn't really care about anything other than getting what it wants.
Sure, you could say that this is just a band and that expecting faithfulness towards it is taking things too far, but if someone is unfaithful towards smaller things, they're probably unfaithful towards larger things as well, from personal relationships to religious convictions...
In other words, the unnecessarily nasty negativity directed towards the band in this forum is really a symptom of a greater problem.
The members who try to keep things predominately positive here, even in the midst of constructive criticism, are trying to maintain a sense of overall faithfulness to the band itself, not enforce any type of oppressive censorship.