I agree that unnecessary markup is... unnecessary. But there are two sides of the coin, on one hand we don't want people to have to install MS Frontpage (or whatever it is called) and have three years web design experience. But on the other hand, most Wikipedia pages are rather ugly and boring. They are like just text! I mean who wants to read four pages of NPOV encyclopedic text where the most interesting things are the paragraph breaks? :-) We're modern people with attention spans measured in seconds.
For example, take the Rambot* city pages, how much better wouldn't those pages be if their information was presented in a more attractive way? I have already complained about the lack of pictures, but as that problem seems to be unsolvable unless someone spends a million dollars on lawyers researching copyright laws, we have to find other ways to make the information pretty.
Currently the easiest and only way to make pretty articles is to use html. It has the disadvantages that it makes it harder for most editors to edit articles and someday it might cause severe browser incompatibilities and problems for disabled users. But isn't that a problem with all new features? I'll bet someone already has asked themselve how to edit the table of contents...
So instead of letting the not so smart people be a hinderance for the way of the future lets make them smarter by providing good documentation and make everything as easy as possible so that everyone can be happy.
BL
* - Everyone seems to complain about Rambot so I figured it would be safe for me to take a potshot too, but it was just an example many other articles suffer from the same problem.