@Christina Warren -Well put. As has been discussed at wltc, time is what drives people to paid models in plugins and themes. The more valuable your product the more demand for your time. I rarely get to work on my own stuff, but I'm not good at saying no.

The codex is good, but there are lots of holes in it and it can be skimpy on examples, unlike php.net. But it highlights the problem of lack of incentives.