That HTML in e-mail is a bad thing is common knowledge. Everyone with a slight clue says it is so everyone believes it. But as the French would say: I have a doubt. I suddenly see very little reason for this hatred for HTML. I can see how some people with browsers without HTML support might not like it, but hell, get a better browser for gods sake.
I think this is just collectivism taking its course. Oh, see what they are doing. Lets agree with them.