I did pay to join SL; it was at a time when Linden Labs was still charging for a Basic Membership. It was a one-time fee, and it was not too price-y to join

. The fee is what enables L. Labs to employ people and make improvements

.
There are some people whom make quite a good "living" from SL. That's a good thing, since they're applying their abilities and creativity in ways that also suit their personalities and so on.
The only features I find missing from SL, which I think could make it better are:
- Voice Activation (for those of us with mobility limitations)
- A desktop module (for working off-line)