That doesn't surprise me in the least. Someone looking for "an 'adequate' sailplane/motorglider for casual/fun-flying use" is looking for ease and convenience of operation, not maximum performance.The consensus might surprise you: L/D in the 30-32:1 range, easily trailerable, self-launching.
I got my glider rating this past April at a commercial glider school, and enjoyed the hell out of the flying*. Unfortunately I have not yet had a chance to log any more glider time. We have a "local" club ~40min up the road that I'll probably eventually join, but so far I just can't justify it.
- They only operate on weekends, and until about a month ago I worked weekends.
- Being a club, you need to stick around and help out/participate. That's not inherently a bad thing, but what it translates into is the expectation that if I'm going out there, I'm out there all day and most of it won't be flying--and that's just not going to work with my current family situation. I can't justify a full day at the airport every week (or every other week) with a young child at home, an unfinished RV project, and other commitments, just to get an hour or two of flying in.
- They have the US-standard aerotow model (read: high operating costs, extra manpower requirements).
My interest in gliders is similar to the reasons I enjoy taking a small sailboat out on a lake. I'm not interested in competition and though the badge system holds some interest I'm primarily just looking to stay local and have fun. A self-launch glider would free me from the fixed time window and the necessity of having others standing around just to get me in the air (and probably impatiently awaiting their turn), and makes operation from "regular" airports a little easier. Easy trailerability has obvious advantages.
I started taking OP's survey but realized so many of the questions I don't have the experience to be able to answer--and it seems primarily geared towards competition flying, not a fun/recreational flying that I'm looking for.
*unfortunately I had very limited opportunity to do any thermaling/soaring; the weather was less than desireable for that and admittedly the school is much more a ratings mill than a soaring school so they didn't really do any practical instruction on the matter