Composite might be garbage or you might just have gotten a dud. I know other people who've bought a top of the line instrument and for some unknowable reason that particular unit was stillborn. A professional woodwind player who comes in the shop told me about his friend who purchased a $10,000 flute that is a model everyone who's played it says is awesome but which for that particular instrument sounded like student level garbage. But maybe composite is trash. The first guitar I owned was an ovation (rounded fiberglass backed) which I received for Christmas. Holy hell did that fiberglass back make it sound terrible.
Also, I know those ovations well. In high school everyone liked them because they were loud. But I couldn’t agree with you more, they sounded really thin. No heart; kind of synthetic.
When I walked in and the tech saw the guitar I was holding he said, “I know exactly why you are here.“ Apparently they are garbage.