It does look superior with "the bars", but its not because of the bars. Its because it looks ridiculous to stretch and distort the image. I always watch programs in their OAR (original aspect ratio).
Besides, burn in is not much of an issue anymore on modern TVs. Theoretically, you could burn in an image, if you paused a 4x3 image for hours or played a video game for 10 hours straight (static video game scores and graphics in the corner, etc.).
But you won't have a problem watching a few Three Stooges episodes. Chances are, you'll be mixing in HD & widescreen TV shows and DVDs (or Blu-Rays) and this will mix up aspect ratios.
And if someone isn't watching HD or widescreen DVDs on their widescreen TV, then really was no point in them buying it to begin with.
I have two large plasma TVs (50" and 65") and have never had 1 problem. I watch plenty of Stooges, Seinfeld, and other 4x3 classics alongside my Blu-Rays and HD programs. There are a lot of rumors out there. I work in the professional post-production and DVD authoring industry and I know what I'm talking about.