Even if you think there is a direct link between this tax issue and the DDCI (which I can't see myself) I would wager that there isn't anyone in Irland volunteering to pay more tax than the statutes say they have to pay. Not one.
If the tax laws allow U2 to legally save money then change the laws but I really don't expect people who are raised to wear leather trousers and be the embodiment of self-regard and solipsism to walk around in a hair shirt when they are off duty. The fact that people who we, as a culture, encourage to live that life do anything at all for anyone else is a miracle of sorts. If you want to beat Bono up then beat him up for having written nothing of note for 20 years. That's fine. Surely the double standard is to expect the mega-successful to be any more altruisitic than the rank and file of the population?
As for the Guardian they should know better than take the bait.