1. I would not judge Wilco by their two Mermaid Avenue records. Though there are a handful of good songs on each (most of them the ones with Jeff Tweedy on lead, not Billy Bragg), much of both are pretty mediocre. Any Wilco concert that featured the Mermaid Avenue material as its star attraction probably DID suck compared to when they were highlighting other albums.
2. Though the 80's did have it's share of good ROCK bands, both British, and American, I would say the 50's were a much better decade for MUSIC. Rock and roll was at its vibrant origins. Country music was REAL...before it went all pop...and jazz was still a great thing...before it went all fusion-y and smoooooth.