It just makes it a lot harder to deal with such pages: if you HTTP-redirect straight to the target page you're missing the link back to the redirect page. (And that is *crucial* for editing work and vandalism cleanup. It is non-negotiable.)
I feel I should point out an implicit fallacy in this. It is non-negotiable that we need a link to the redirect page. It is *not* non-negotiable that we can't return a 301 HTTP redirection.
The only other way I can think of that you can get from a page to something that redirects to it, is via Whatlinkshere. This is useful, but not perfect because you may have to browse through long lists to find the redirect you're looking for.
My suggestion would be to add a list of "redirects to here" to the Edit page of any article. We already have a "Templates used by this page" list; this would be a useful complement.
Once we've done that, we can renew the discussion about HTTP redirects, because now the "Redirected from" link is no longer strictly needed.
There's also the hacker's non-UI option of allowing "?redirect=no" at the end of /wiki/ URLs (rather than only /w/index.php URLs). Then technical/experienced users won't even need to go to the Edit page.
Timwi