I used to maintain the point of view that having redirects all over the place (as long as they always go to the intended article) can never do any harm, and in fact they keep the pages accessible under old links (i.e. deleting them would break links elsewhere on the Internet).
I think some sort of technological solution (hopefully a light-weight one) is needed to fix that problem. There seem to be two main types of redirects:
1. Titles under which one might reasonably expect to find an article in an encyclopedia, but which redirect elsewhere because there are multiple legitimate names for the same concept. An example is [[United States]] vs. [[United States of America]]: both are legitimate names, but obviously the article should only be at one or the other. Same with scientific vs. common names of many organisms, and so on.
2. Titles that should not exist in an encyclopedia, either because they are misspellings, just kind of ridiculous, simple variations of capitalization, or something else, but which might conceivably be searched for. This also includes old names, like the former subpage naming mechanism.
Clearly these two types of redirects serve useful, but different purposes. We might want those in 1. to show up in allpages with a "See [blah]", but perhaps we wouldn't want those in 2. to do so.
Would it be possible to implement some sort of mechanism whereby a redirect can be flagged as merely a convenience or technological measure, not a legitimate alternate article title?
Of course, this may lead to some argument over what is legitimate, but I think there are a great deal of obvious cases of not legitimate names that this could take care of (like all the former subpages, misspellings, or variations on capitalization).
-Mark