I have never heard of sound bars falling apart after a couple years, is that common? Every piece of sound equipment I've ever bought has lasted at least 15 years, my sound bar is 5 years old.
In general I think the sound bar audience is different from the hi-fi audio audience. I was fine with using the TV's built-in speakers until LCD TVs took over from CRTs and the built-in speakers became much tinnier and quieter because they couldn't fit quality speakers in a flatscreen TV case. I suspect most people who buy sound bars are in a similar situation.