bad bear, there are a number of issues that need to be considered. But first, don't underestimate the inertia associated with changing things - often for reasons that are valid for significant proportions of those affected.
Let's think about going to CTAF, or something similar, at an airport which caters for commercial passenger-carrying aircraft - what level of service, or of safety, are those passengers entitled to expect? What level of service do they tink they get today - it;'s an interesting topic which, to my knowledge, has never been properly investigated. In part, at least, this question almost certainly was what led to the legislation that requires ATC at an airport in the UK where an aircraft can carry out an instrument approach.
However, there often appears to be confusion between the concepts of an IAP and an ATC service. Although it may seem to be stating the bleedin' obvious but if a pilot needs to make an approach to an airport and can't do it visually, he needs an IAP - if he wants to be separated from other aircraft he needs ATC too. The idea of pilots sorting themselves out by talking to each other is not well established in the UK, particularly in the eyes of the CAA people who set the rules. Indeed, I think there is some evidence to suggest that it doesn't work very well - I recall at least one AIRPROX in Scotland where the FISO provided all of the correct information but the aeroplanes still came close to colliding.
Despite this, some 8 or 9 years ago the CAA proposed permitting IAPs to be conducted where a FIS was available but it met a lot of opposition and I imagine it was dropped because nothing further came of it.
But all may not be not lost. It is quite possible that EASA will sort this out - or at least attempt to achieve some consistency across Europe.