gpn01,
I think you chose a very
good example to illustrate that glider pilots (and some others) perhaps need to think "outside of the box" in these days of increasing air traffic congestion. The UK "big sky" is getting smaller.
Imagine this situation: A transponding, TCAS equipped powered aircraft, in receipt of a Lower Airspace Radar service, flying in IMC in Class G at the correct quadrantal level, collides with a glider thermalling in cloud, the pilot of which was not in receipt of any ATC service, had not announced his presence, had no transponder and was invisible to radar. The wreckage of both aircraft falls into a congested area, causing further casualties and damage on the ground.
What would be the general opinion of the public? What would the press say? Who would be held responsible? Increased legislation and restrictions would quite possibly be the outcome, which would help no-one.