Documentation should have many examples, which would show how to use JCPT in practice.
I do not completely agree with you. As my personal experience, the number of examples doesn't matter. And that is exactly why I came back to here from JME. JME has a full bunch of good examples, tutorials and tips and tricks on how to use JME. But after going through all the tutorials, looked through all the samples, and posts on the forums, i cannot even setup a robust collision detection system. And if you looked through the forum, there is not even any meaningful posts about collision system.
I my opinion, the engine itself is more important. JME, until now, doesn't have an easy to use collision system (i don't mean they don't have, they can detect collision for you, but how you put your objects, your own task!). In terms of support and service, other engines have much documentation, but not enough to setup a game as easy as the two examples given by Egon; other engines have numerous posts in the forums, but many left unresolved or at best, linked to a scholarly paper, which you are left to do the implementation.
I do have the initial feeling like you - why the support & document just don't seemed enough. But now i come the understand. The reason is not because the support is no good, but because i am to noob. It takes some time to get used to it.
Anyway, need help, just post. There are many people who walked thus far, and who are willing to push us forward.
Cheers.