I dont know about anybody else, but after busting my ass trying to make my site XHTML and being told "oh, we lied about XHTML", I dont trust the W3C has my needs in mind anymore. The new crap they push out is just not interesting or relevant to what I want from a markup language. I feel more like it is trying to push a philosophy on me rather than a useful tool.
What the hell good is a dialog tag to me? Google doesn't give a shit about my semantic markup so it wont improve my search engine rankings. I'll have to tear down the browser style and rebuild it in my CSS file, so it would be a pain in the ass for me. I dont give a flying fuck about supporting people who want to leech my content by describing the content better, so I'd rather not make it easy for them either.
I would like to make a bold prediction. Any new version of HTML or XHTML pushed out will never become as widely adopted as what we have now. Whatever is finally released will be met with a resounding yawn. We will all have jumped ship to silverlight or flash, which does what we want now, rather than wait for another three year lag before the new markup is actually useful. It might be marginally useful to screen readers though but that it will be abused by web authors for viagra sales, it will be ignored by them too.
In three years, I predict fully 75% of all cool stuff on the internet will be silverlight or flash based. At that time, O'Reilly will have named it "Web 3.0" and slashdot, while 100% based on silverlight, will have people bitching about how it is all hype and people were using XAML back in 1985... There will still be people bitching about how it doesnt work in lynx and all we really needed was an 80 column text file.
Within 10 years, the HTML will be only supported for legacy apps and the W3C will be disbanded. At that time, all of us will be bitching about how silverlight or flash is holding us back and the cycle will repeat yet again.