I suspect that, if indeed airports are more reluctant than before to allow this, it is due to today's "cover your ar*se" management attitude, duty of care, and all the other legal bollox which increasingly penetrates every facet of our lives (and the vast majority of which has never been tested in the courts - in the specific aviation circumstances in question).
I don't think it is due to more people flying DIY GPS approaches, although the careful use of GPS has made those far safer than say 20 years ago.
One has to remember that most airports are the last surviving pockets of 1970s British Leyland working and empire building practices, and this is true all over Europe.