When I'm out walking, I can occasionally see TVs in peoples' livings rooms. A lot of them watch 4x3 content stretched on their HDTVs. Not zoomed, but stretched. I can't understand why anyone would want to do that.
You'd be surprised how many people don't even think there's anything wrong with the picture and happily watch 4:3 programs stretched all the time. I actually got accused of breaking a friends TV after I set it to auto switch to the correct aspect ratio.