Coming from a library science standpoint -- it's fallen out of vogue with the general public. Things like Google and other web-search engines show that you can get a reasonable level of findability with minimal human effort through use of full-test searching.

Unfortunately, as time is showing, it's very possible for people to game the system by inserting false or misleading terms, and search quality suffers when there are many words that describe the same concept (synonyms), or many concepts used by the same word (homonyms).

Cataloging has its benefits, and can lead to improved findability in many situations -- but it takes work. And it requires continuous maintenace, as there has to be a group that deals with decisions about adding new categories, or pruning old categories, and work required to reclassify the existing items as the word list changes.

So basically -- it's a lot of work. The work grows above linearly for both size and time. (I don't know that it's exponential, though, maybe for small values (1.01^size) or similar).

Perhaps this is something that AnnoCPAN can add in, so the work can be distributed across multiple people. (but then you have to make sure that everyone is clear on exactly what the categories are, so there's consistent catalogging).