Big Bad Voodoo Lou, like you I’m a young indie snob with no time for Credence, Acca Dacca, Skynyrd or The Eagles, and I’m going to echo rackensack. When I think of early '70s bands, I include Big Star with Lou Reed and Iggy Pop as what all those people should have been listening to if they had any sense. Big Star have strong indie roots (The Replacements have even written a song about them) and should no way be lumped in with the '70s bands you mentioned. Give them a go. You won’t be disappointed.
As for power-pop, here’s my nutty theory, and because it’s only new, I haven’t had time to iron out the holes yet, so be kind.
But if you look at contemporary music, as other posters have alluded to, bands that make pop music with a bit of driving guitar are popular. Everyone remembers that Teenage Dirtbag song from a few years back, right? How about all those Smashmouth songs that get played on the radio. And Green Day and No Doubt, as GargoyleWB mentioned.
So there’s my idea. Powerpop is popular, but, like nearly everything else, the good stuff isn’t popular. Take pop-punk as an example. Now, I’m actually quite a big fan of Blink 182 (and I hope that admission doesn’t make Big Bad Voodoo Lou dismiss my earlier statements on Big Star - I’m usually a lot more snobby, OK? Trust me!), but anyone who believes that Blink 182 are great because of the punk is deluding themselves. When I listen to Blink 182 - and I think everyone else who listens to them is in it for the same thing - I’m listening to them for the melodies. If I want punk, I’ll listen to the Clash; Blink are for the pop thrills. Sure, they’re not exactly power-pop; there’s a bit more power, and the pop isn’t as smart, but the basis is there. After all, if Stacey’s Mom had a bit more snottiness, and was a little bit faster, it’d be a punk-pop song. The same goes with all those Good Charlottes, Sum 41s and Simple Plans. It’s basically power-pop, though certainly not the best out there.
So maybe power-pop is a popular genre, but the popular power-pop isn’t always recognised as power pop.
I’ll also say that genre’s like New Wave had a lot in common with power pop and were very popular. The Cars are certainly power pop. Elvis Costello, though perhaps not strictly power pop, certainly knew his way around a melody and attacked his songs with enough power to qualify.