The golf club mentality thing doesn't seem to apply at power clubs as the power clubs seem to be run as businesses with services (landing fees/parking/etc) sold to members without work being expected of the members. Gliding clubs are run as societies on a not for profit basis, so require their members to get involved in every aspect (CAA/BGA compliance/accounting/running the launch point/driving the winch/etc) and this makes gliding clubs a haven for jobsworths and for those too lazy to pull their own weight. This in turn creates the friction and the feeling of 'being watched' lest you don't make a reasonable contribution. Its the feeling of being watched that give the golf club mentality feeling.
It also has to be said that the gliding club system brings out the best in most of the members and keeps the flying cost much lower than if it were done the same way as a powered club.
Becuase I'm not a team player, I will stick with powered flying but I miss gliding enough to be tempted by motor gliders.