<p>Why are there not more opensource easy to use charting libraries for Java?. The only successful opensource project in this area seems to be jfreechart, and it doesn't even have any documentation or examples available.</p>

There is JChart which is all open source.  I'm not sure exactly what you are graphing and how you are graphing it (servlets, swing, etc) so I would say just look at a couple different ones and see which works for you.
http://sourceforge.net/projects/jchart/
I've also used JGraph but I've only used their commercial version.  They do offer an open source version however:
https://github.com/jgraph/jgraphx