Again, I don't use them either. But in theory, people would search for articles based on the relevant components of the SCP they were looking for. The standard tags are "SCP" and the object class; the attribute tags, the ones Mackenzie came up with and standardized across the board, are probably the most convenient and simple way of keeping those tags even tentatively searchable by actual humans. The two things writers are likely to do (since it's what they were doing before, and by "they," I mean "me") are to use redundant tags ("octopus", "octopi", "octopudiformes", "cephalopods") or irrelevant tags (an SCP about an red octopus named Steve that teleports submarines to Mars being tagged with "red," "octopus," "Steve," "teleport," "submarine," "Mars", etc.). Mackenzie fixed the first one, which was obviously necessary, and also the second one, which is necessary in a way that isn't necessarily obvious. For tags to be effective search tools, there has to be a controlled vocabulary, and somebody to control it. Mack gave enough of a shit to take the reins, so she's it. I'm seconding everything Quik said: Mack did an unholy shitton of work making the system and does a not-inconsiderable amount of work maintaining it, for no pay and not much gratitude.
Not to say we shouldn't reserve the right to add attributes or tags as the need arises, but what we have now should work for the foreseeable future. Most of the problems users have with tags that I've heard come from inadequacies of Wikidot's tag system (namely, no ability to search multiple tags at once).
