IMO, I honestly don't care what music is classified as or what the 'image' of the band seems to portray. The only thing that really matters to me when I listen to music is whether or not the music is catchy and/or has depth or speaks to me in some way. My tastes in music span multiple genres. Heck, I have KMFDM followed by Sarah McLachlan on one of the CDs I've burned. That said, I can't stand it when somebody tries to discredit an artist's music just because the artist is a 'sell-out' or a 'poseur'. Honestly, there are bigger things to complain about than what kind of person the artist is behind the music and what their motives were for recording what they did. Falsely portraying or stereotyping a genre of music is the only thing that gets to me (i.e. the TRL crowd wowwing over Marilyn Manson and his 'Goth Rock' - yes, I was being sarcastic; Manson is an Industrial artist). Pop-punk bands, to my knowledge, don't do this. Most of the programs I've seen do make reference to older, established punk bands, etc.
I don't see classifying bands like Simple Plan, Good Charlotte, or Blink 182 under Punk as degrading to the British and New York bands that established the genre simply because of the fact that the work of those original bands is what defined the style and will always be what it has been - good, solid music that had an impact. People thought Post-Punk (specifically New Wave and New Romantic, but just in general) music was a blasphemy but out of that has come a lot of great music that also had an impact. A genre of music or the artists that defined it is not on such shaky ground that a pop-friendly variation of the style is going to destroy the importance of their contributions or somehow insult these artists, unless the artists and genre in itself were fake to begin with, which is certainly not the case with Punk. Melodic Punk (what Pop-Punk was called before it went mainstream and morphed into an Emo hybrid) has always had a pop-friendly sound even if a lot of the artists were fringe in the beginning. I wouldn't say they degrade the integrity of New York Punk or British Punk or California Hardcore, etc.
Anyway, I think Simple Plan is ok. They're not my favorite band in the world, but I did see them at Warped '03 and Grad Nite and enjoyed both shows. There's a few songs that I like, even if I don't have their albums.