I wonder why people don't use PLT that much. It has libraries, docs and tools, and its scheme(maybe thats the problem?). Its a cool environment, I like it very much.

Well right now you are using an application -- Hacker News -- that is written in pg's Arc language which runs as an interpreter on MzScheme which is part of PLT Scheme.

Why don't more people use DrScheme, HTDP, etc.? This is a question about learning, culture, change, etc. more than any particular environment, method, etc.

The libraries aren't good for PLT scheme, at least for web development. For example, want to parse an RSS feed? Compare http://www.rubyrss.com/ to using HTML Prag (http://www.neilvandyke.org/htmlprag/).

Want to do billing? openid? you are out of luck. But having said that I'm experimenting with a site in PLT Scheme (and I know a couple that use Kawa as well).

For the same reason why people don't use scheme: they don't understand it, so they don't bother with it. I know scheme myself, and I don't bother with it, as I've not had the time to really learn the libraries that come with plt.

For some reason while I tried it for several months it never felt... sticky? I just never felt like it quite fit for me.

Of course Clojure showing up may be part of the reason for that.

You are overestimating the significance and impact of Clojure. The language has potential, but it hasn't stolen mindshare from Scheme or any other Lisp dialect for that matter. People going to Clojure are coming mostly from non-Lisp languages. Lispers are quite happy with what they have; there are standards compliant, mature Schemes for the JVM. Clojure offers nothing to Schemers.