Yea it’s worthy of a major. It’s hosted the PGA championship 3 times and the Ryder Cup.
I would answer the previous question this way, I have personally played four courses that have hosted majors. Erin Hills, Whistling Straits, Ocean Course and Valhalla. It would rank 4th of those on my list, and Valhalla is not one of my favorite courses, to be honest. But that is just solely on the golf course itself.
However, due to the way it was built, it is a great venue to host big events, easily accessible, can accomodate large crowds plus corporate amenities. Louisville always supports the hell out of the events held there. And of course, the fact that the PGA owns it is a huge point in its favor. So, it is at least as good as Chambers Bay, and some of the other courses that the Open and PGA have been held.