Sometimes a band, and music (and life) in general, isn't about how difficult it is. Finding something amazing in the simple is its own kind of genius.
Agreed. Scandinavian Death Metal features complex and non-standard time signatures, key changes in the middle of musical phrases, and instrumentation requiring freakish skill with their instruments/voices. You don't see Scandinavian Death Metal getting much attention.
For me, I wont play the "overrated band" game. I was there when Nirvana hit, and while I was pretty 50/50 on my enjoyment of each individual song they played, you cannot deny what they did to music. And to claim that their music was simplistic, and therefore not that good, is to completely miss the point. They came out of an era of music where the standard, what you had to be to play rock music, was Slash or Bucket Head or Eddie Van Halen. Synthesizers and falsetto voices. Music that was a spectacle in its presentation. Nirvana hit the collective nerve of the pre-internet world and literally, overnight, changed what popular music sounded like. People who have grown up being able to listen to Pandora or Slacker or search YouTube for Fluvian Throat Singing or whatever else you want don't understand. Imagine a world where the only music you could listen to was local broadcast radio or the tapes/CD's that you paid for. And so yes, their music was simplistic in a lot of ways, but that was the point. Their style sort of made it seem like they'd just gotten off work at a gas station before they got on stage, but that was the point. So, while I didn't necessarily like a lot of Nirvana's songs, but I recognize what Nirvana did.
And that's the way that I am with a lot of bands. Red Hot Chili Peppers, I haven't liked a song of theirs in probably a decade, but that doesn't mean that I don't hear bands now that, whether they know it or not, owe their sound to what RHCP pioneered.
The Beatles? I actually strongly dislike most of their music, but that doesn't mean that I deny that everything I hear on the radio/internet today owes its existence, at least in part, to the Beatles and what they did for rock/pop.
So, I don't play the "what band is overrated" game because, liking a band is subjective beyond belief. Music is art. There were dudes who said that Beethoven was an overrated hack in 1827. I'm willing to name off some bands that I don't like that a lot of people do like.