I feel that there are various problems with music in parishes which rely on amateur volunteers for their music.
There is a great lack of training and expertise. This affects all instruments. The organ has a slight advantage here that the sight of two or more manuals, a pedalboard and a bristling array of stops all controlled from a rather penitential looking bench is very offputting to the uninitiated. The guitar comes off worse because of a widespread culture of low limited scope playing and a wide availability of books with title along the lines of "Learn to play guitar in some ludicrously short time." There are even liturgical guitarists who need to progress to I, IV, V. The electronic keyboard also suffers from auto harmony and built in rhythms which appeal to the tyro.
The compilers of currently available hymnbooks do not seem to want to drop material that was transiently popular a long time ago, but is of very limited appeal. Does anyone still use "Kum ba ya" at mass? Other material is not obviously relevant to Christianity except in the most general terms, for example, "Peace is flowing like a river," which does not mention God. As far as I know, only the Catholic Hymnbook actually includes an endorsement by a Bishop, and although it is a useful book, it is too limited in its appeal for most parishes.
Another problem is that much of this music is in a style which developed circa 1970, and was based on one strand of pop music in the popular in the late fifties and early sixties. As commercial music, melody seems to be at a low now. In consequence, the guitar hymns have their main popularity with a section of the congregation aged between sixty and seventy. Those outside that age group do not identify with it. My own children and their friends see it as hopelessly "uncool."
The overriding problem to me is the lack of musical training in the clergy. They are left as the final arbiters of what is done in the parishes, but often have no idea what is possible, what ought to be aimed for, and in many cases, what the expression "in tune" means. Some even have the attitude that anyone who asks for it can have a place on the music rota. No one is to be denied their ministry.
The effect of these problems is that I and many others have been given a sort of aversion therapy to modern music. However, I am often pleasantly surprised when I am away from home or catch a little on tv or radio. However, any attempt to introduce such an item dies rapidly at the hands of the untrained.
Does anyone have even the vaguest idea of a way forward?