I agree with you insomuch as it's ideal for an extension, and argued for its inclusion as a 9.3 feature (looks like Christmas might come early, though). However, I concluded with this:
Right now the perception of Postgres...actually, databases in general,
including virtually all of the newcomers -- is that they are
monolithic systems, and for most people either "9.3" will "have"
javascript and indexing of JSON documents, or it won't. In most cases
I would say "meh, let them eat cake until extensions become so
apparently dominant that we can wave someone aside to extension-land",
but in this case I think that would be a strategic mistake.
http://archives.postgresql.org/pgsql-hackers/2011-12/msg0078...So this is definitely a social problem. Why not move UUID out of the core? (not uuid-ossp, which implements generation, but uuid parsing and storage) Because, for now, one cannot assume extensions for really common useful functionality.
Luckily, I think things are on the right path to at a future juncture that even a commonly desired data type can live as an extension.
