People have said they've sold out, changing their music just to make more money. I think the people who say this don't realize that 80's music is stale in the 90's, except for the brief nostalgic bursts. I wonder why U2 is really the only big 80's group still around and successful. Achtung Baby has been described as futuristic and dark. Zooropa was downright ambient.
POP is a mixture of both.
I would say that Pearl jam has departed from their previous music in their latest attempts. U2 has not sold out. They love to make music. When they have time off, they take lessons, do side projects, they do things that show their commitment to making U2 better. POP was, in my opinion, their most personal album.