For basic tasks, I actually prefer Mediawiki markup over a design-mode HTML editor. I find it to generally be more concise and easier to type, plus linking is much simpler, and it's easier on the eyes when reading or editing versus HTML.
E.g. this is much easier to type and read later (if you edit):
Hey! I just '''love''' this new [http://www.google.com/ website]! It's so amazing and ''awesome'' and stuff!!!!!111one
New paragraphs and lists are cool too:
* One
* Two
* Three
# One
# Two
# Three
than
<p>Hey! I just <b>love</b> this new <a href="http://www.google.com">website</a>! It's so amazing and <i>awesome</i> and stuff!!!!!!111one</p>
<p>New paragraphs and lists are cool too:</p>
<ul><li>One</li>
<li>Two</li>
<li>Three</li></ul>
<ol><li>One</li>
<li>Two</li>
<li>Three</li></ol>
It produces much more consistent markup on the server end than the browsers' design modes can produce and it's still readable even if you are looking at just the source with no formatting (and I'm even being nice here, because a browser's HTML editor would put the above in with no line breaks to make it easier to read.