I asked my 10€ bill to write up some blender docs, didn’t work.
See, if anyone of the devs had the time to set up the account, bookkeeping, payment management and information transfer for paid documentation writers they’d use it to develop the engine or write javadoc.
It’s actually a shame that the excellent documentation that lots of work went into has to be defended at all. On top of that theres at least two available books, where the work put in was and is driven by money as you suggest.
Yes, you can criticize a lot about the engine, the docs and everything around it. But that isn’t productive at all because jME isn’t some product where the value is in how good it compares and sells on a market. The engine and everything around it is a product of people being excited about what they do - constant criticism is sure to dampen that excitement.