it will result in the aircraft not being able to land in some European destinations if the weather is not VFR.
I really find that hard to believe. Especially because if this is a regulatory issue, it's not just a question of the weather - in the US at least (and I'm pretty sure elsewhere) if you don't have required equipment for IFR, you can't even file IFR. And I can't believe that airlines would buy aircraft that can't operate under IFR in their own country! Since the only 100-200 seat aircraft on the market are the 737 and the 32x, that would end up being the case.
There must be more to this...