People bash over ie6 just because it was revolutionary at that time and some people are still using it. Yeah, it's a pain to deal with as it's a pain to deal with any old technologies. Try to support Netscape 2.0 for fun.
I don't know that I'd call IE6 "revolutionary", but it was indeed an excellent browser for its time. As terrible as its standards support was compared to later browsers, it was exemplary for its time.
But it's impossible to ignore the way Microsoft reacted to winning the browser wars by shuttering the IE team and leaving web standards effectively adrift until Firefox came along and starting taking market share. Whether you call it reprehensible or want to call it a "good business decision" that just happened to be bad for consumers and the web, that will always be the legacy people remember about IE6.
