Yes eventually styles change and stock photos taken 10 years ago no longer cut it.
With regard to image quality the situation is less clear. Magazine pages aren't getting any bigger, offset printing resolution isn't increasing (correct me if I'm wrong) and as content migrates to the web, resolution is even less important than it was on paper.
CD audio quality (12 bits at 50 kHz I think) turned out to be more than good enough for most people - higher definition audio formats never sold, and todays downloaded MP3s aren't particularly high quality. So while a 4 MP image is definitely out of date, it's not clear that 12MP won't be enough, anytime soon.