There is plenty of GA around Europe despite your rather blinkered view.
A lot of ultralight stuff at a low level, doing short hops around the local clubs, but very little longer range touring goes on. As you well know if you have an IR and use it. Especially true in France (according to French pilots I know personally), which I find really odd. I've done quite a number of trips to the radius of say Greece/Spain and on most of them did not see another GA plane (once outside the UK).
I merely played devils advocate and asked the question of what would people have done without an IMCR.
The loss of the IMCR would be unfortunate but hardly the end of the world and it certainly is not the only reason that people are able to do any practical flying.
That's because
(1) people all over the world fly illegal VFR, and
(2) people living in countries with nicer weather have less need for instrument privileges
The IMCR formalises what people do anyway and makes it legal, in the process adding access to published instrument approaches which one could not otherwise use without drawing attention.
Now, we could have a perfectly good debate on why legalise something which people do anyway and which is impossible to regulate.
I think the answer is that there should be a legal framework, not just because it is "right" but in a more practical sense because it enables the pilot to legally land on an instrument approach without his risk management decisions being affected by the prospect of getting done.
A VFR only pilot who is instrument capable isn't going to ask for an IFR clearance unless he is utterly desperate. I would still do touring if I was limited to VFR but the flight would be strictly outside CAS and would have preplanned GPS "approaches".
The death rate in France is double that of the UK and much of it is CFIT which is exactly what this is about.