Would fit the expectatives. It's a commons mistake
among beginners.
However, not only they have a different syntax for brackets, also for
separators. So if you "fixed" it, you could end up making a link as <a
href="http://www.example.org/|Nice">site</a>
Also, it would further restrict available pagenames: Things like
http://en.wikipedia.org/wiki/Http://www.google.com *do* exist!
It is however an interesting proposal, as you wouldn't need to recognise
[http:// links at all. You would simply define http: as a special
namespace linking to that page (same with ftp:, mailto:...).
You could even do something really clever allowing articles to be
created in the http namespace and have redlinks to them go directly to
the webpage (the link wouldn't actually be red, of course), but if the
page exists, it displays with the title automatically a link to the
webpage, or something like that.
God knows why you would want to do any of that, but it would be clever. ;)