Forgive my bluntness. I generally despair about the over-regulated, over-taxed, over-restricted misery of European GA. When I read some of the ways people think about (not) supporting the representative organisations (and compare that to the US), I think we deserve it.
That is indeed a very blunt statement. First of all, given the good work performed by Mike Cross and Martin Robinson, if you're living in the UK, there is a clear case to join AOPA UK for the reasons both Mike and yourself mention. Especially Martin is actively lobbying the UK MEP's to get them to reject the FCL draft proposal when the translation reaches them around July 15th.
On the other hand, some "representative" organisations have been extremely ambivalent about the N-reg stance. I would like to cite PPL/IR Europe as an example, with Jim Thorpe not really defending our case vigourously enough so as to avoid mishaps like FCL Annex II. As an FAA IR pilot, joining PPL/IR and contributing to them would be a natural thing to do, especiallly because their Belgian arm is particularly small and could use not just the contribution but also the active support. But when he accepts statements like "The FAA IR is insufficient to navigate the UK airways" at face value, I run a mile.
I hope you do not qualify this behaviour as cluelessness or a tendency for unrealistic expectations. By contrast, when Alexandra started her campaign of the N-flyers, I jumped on it and contributed "to keep the aspidistra flying".
Generally, people are willing to join organisations that seem credible to them and that provide a service (at the very least open and regular communication, pilot goodies as an extra).
In the current situation, we have to play with the cards we got dealt. That doesn't exclude vigourous activism : calling MEP's offices and writing letters; writing to the Commission to complain; applying to the Transport minister; and for us Belgians, calling Finserve and see how they feel about losing out on about half of their insurance premiums.