Green Day may have sold out to hit it big. That's fine; I'm not a big punk fan, but I love Green Day's pop punk, so good. Sell out. Make yourself more appealing to me. I'm here for it. As long as I like the change. If not, you're a sell out and you suck.
And yeah, lots of 1980s rock and roll bands found out they could make a bunch more money with power ballads than with bluesy, driving rock. Top of the list is one of my favorites: Aerosmith. Permanent Vacation is tolerable, but when they hit it big with Angel, it was over. Did all of their music after that suck? No, but most of it did. Def Leppard, definitely. I didn't know Whitesnake before they sold out, but I believe it. The late 80's/early 90s hair bands were basically a collective sell out. I get it, they made more money. Good on 'em, just not good for me.
On the flip side, the Clash--like Green Day--got better when they moved away from raw punk.
Maybe I just don't like punk that much.