I don't see a problem with painting a bike if you want to. I mean it was painted by the manufacturer. I personally do not unless the paint is beyond hope or someone had painted it before I got it. It would be tragic to paint some of the C&V bikes out there and I love the patina on older frames. The paint is pretty beat up on my Schwinn Speedster, but it earned every scratch. I think painting it would destroy any character it has.
I think some people are wired so they have to have something new and shiny looking. For instance, if 2 used mountain bikes are sitting side by side, a shiny box store express and an older (cosmetically challenged) Specialized, you just can't convince some people the Specialized is the better deal.