Matt, I think you're right.
And why shouldn't they be? As you get older you change. Your testosterone levels drop and the fire and rage that burns as a teenager is replaced with something calmer. I remember Sting saying in an interview with Jools Holland once that the point at which he had achieved everything with the Police and they were the biggest band in the world was when he was least happy. It is often the struggle to achieve that motivates a person. Once you have made it, you need new ambitions. U2 have done it all and I could quite easily see them calling it a day completely in the same way REM did, by just saying we've done what we wanted to do as a group. Whatever it is, it's not everyone's ideal to do the same thing for your whole life. The world is a big and exciting place and I would expect them all to be doing other things, as they are. The only real reason for them to exist is a selfish one ... their love of music and of what happens when they play together. When they yearn for that again, stuff will happen. They will be back but I just think they don't need it as much anymore and that's absolutely reasonable.