I dont agree.
While a GA may be necessary as an emergent issue, for the most part, a GA is the result of a failure much further back.
Given the amount of redundency in an approach procedure, as the study illustrates, the need for a GA is mostly due to pilot error.
A GA really fuks up the DEP queue, crossing, LAHSO, and generally, the airspace. It is, and should be considered an emergency procedure.
I have seen much more abuse of GA due to pilot error (overspeed, underspeed, etc), much of which could have been prevented prior to needing GA, than actual necessity of use (such as runway occupied)
Conclusion: I feel that GA is overused as a result of pilot error, not emergent issues. Dont train the pilots to use more GA as a means to supplant better pilot training.