I appreciate all the fine arguments you've made here, xris. As it turns out, I've finished with the task I set myself, tagging threads with about 25 postings or more that include at least one posting in 2008.
The task gave me a chance to consider how I would tag a variety of items. Let's take the "inspirational" tag, for instance. Since members do specifically ask for shows with inspirational themes, I thought this might be a useful criterion when searching Suggestions. I agree with you that a large fraction of the requests here are of the "something like X" variety, but there are also dozens of requests for some combination of romance, action, and comedy, and the occasional ones for things like "production values." There are also some members who make more thoughtful requests. Often these threads get a lot of traffic, and much of it is well-informed.
However, I think my perception of how tagging works is rather different from yours and probably Jelsoft's (and, for all I know, everyone who knows about "social networking" about which I know nothing). Everything about tagging seems so global. If I click on a tag in the cloud I get all threads that are so tagged. Restricting searches to specific forums, though possible, isn't obviously supported on the tag search page.
I also thought that perhaps we'd get to see tag usage patterns by forum rather than the global "cloud." That way someone could visit a page like tags.php for the Suggestions forum and see the tags in use there. That would certainly make tagging a useful feature in Suggestions, since people could start with the tags page to get a list of existing relevant threads. It would also enable members to build up a common vocabulary of tags relevant to that forum.
Since you've been browsing my tags (how can I do that, by the way?), you can see I've studiously avoided ones like shounen, shoujo, etc., and tried to stick with obvious content genres like "romance." Then there are the variety of tags that you mentioned that are descriptive of the content like "maturation." Shows as divergent as Hikaru no Go, Dennou Coil, and Twelve Kingdoms share this characteristic. Given the primary audience for anime, maturation seems a common and likely theme.
As for how we might build up a common vocabulary of tags, I'll discuss that in the
Tags thread over in Forums and Site Feedback.
Maybe this thread should be closed with discussion redirected to the Tags thread? If so, I'm sorry if I diverted the conversation over here.