No need to change airspace classification . Just implement class D around airports that receive commercial traffic, or link the CTR with the class C airspace above in HX.
I fly gliders, GA aircraft mostly in Europe and was a Controller for 35 years.
The collision in Montpelier plus the Ryanair pressure forced the French DGCA to do just that some years ago.. Cost money of course , putting real controllers instead of AFIS agents in small airports , but risks of collisions are mitigated to the max that way .
In Germany where the problem is most . A recent airprox in Mimmingen ,(plus lots of close calls near Ramstein and Hahn over the years ) shows us that it will end up in a collision one day . But basically , like with the UAVs , we are all waiting for one for things to change . Sad.
Blind pew,: time to move to the 21st century : today's Mode S transponders ave very small light weight (400 grams) , use little power and are very reliable . ( like the TRIG 21 for instance :
Trig Avionics | TT21) I use one. You can today couple your batteries to a flexible solar panel, power not an issue anymore )
you said :
What is needed is pilots looking outside and lazy controllers using primary radar.
100% with you with looking outside , but Primary radar (where they sill have it) and the lazy controllers will not help in class E, , as radio contact is not mandatory and the primary return of a modern glider is close to nil.
The problem is the heads of people to change habits, not in airspace classification .