A while ago some bright spark thought to put a DIV around the statement of maths theorems, with a dashed purple border. Today it's boxes with coloured borders for disambiguation notes.
Here's why these are bad ideas:
Firstly, Wikipedia is a wiki. That means source text should be as light on markup as possible. Knowing HTML should not be a prerequisite. We currently have HTML for tables and floated images -- this is something to be dealt with, not taken as a springboard for more. Besides, tables and floated images serve a purpose, which leads to:-- Secondly, wiki markup is structural. This is one of its great strengths: in accomplishes in one fell swoop the whole HTML/CSS separation of content and presentation. Thirdly, there is the aesthetics of it. Wikipedia thrives on simplicity. Anyone can write a plain text article. Granted, there are certain style guidelines, but do we really want to add purple borders to the manual of style? Is the instigator of these pretty tweaks really going to go round every single page to bring them into line? Which bring me to: Fourthly: common sense. Suppose we *do* want a purple border around a theorem, or a pink background to a disambiguation notice. This is *not* the way to do it. If we really wanted this, we'd set these colours in the stylesheet (because that is where presentational information belongs) and we'd somehow tag paragraphs in an XML-like manner: <disamb>This is a disamb.... etc </disamb>. Though even that, IMO, would be bringing too much markup into the wiki source.