"
Gliders are extremely elegant and clean.
Turbines are also quite elegant and reliable,
with the only drawback being fuel consumption.
For self-launch gliders this is not very
important, since only minutes
of climb are needed anyway.

I agree with much of what you say but fuel consumption is actually important
to get the full utility of a self launcher. If you want to do a tour for
example and go from place to place then you often need to relaunch without
refuelling or you may want to cruise a while to get into wave or good
soaring. If you go on a long task and totally misjudge the weather you may
need forty minutes of engine time and most of your fuel in a petrol engine
machine just to get home.