For a project 1.5 years ago, I generated all my html via markaby from _why. It really kept my html very very clean, but the downside was that the designer guy didn't understand what the heck was going on so I haven't considered using it since.
you cannot take a delivered html document and convert it into whatever html-generator you use. the designer will have no clue how to use your (hand) converted file in dreamweaver to make small changes. in the end, it just makes life harder for everyone and costs more money.
However, given that business are formed to turn a profit, the standard workflow will remain unchanged until it is profitable to do otherwise.
If a markup-generating DSL was simple enough for designers to pick up quickly, it would make good business sense to push them through the transition.
Designers being able to do it isn't the problem, justifying why designers should need to is the problem.
any DSL which generates markup must be more concise than the markup itself
a more concise language will be better in the long run
HTML is a designers tool, and generating it is basically a programmer working by what they perceive as an annoyance by shooting someone else in the foot. It also smacks a bit of "I see no value in how this is done so I'm going to generate it from code", which I think is ignorant, but that's my opinion.
I also don't think it's as maintainable, but I have no evidence to back this up (but I really don't want to be the guy who has to go decipher the code that generates a website two years later, I'd even rather deal with ColdFusion).
I thought the modern idea was that CSS is the designer's tool, and HTML should only be used for marking up content in the most semantically "correct" way (which has nothing to do with design).