I understand the idea of a headstock shape being accepted as a trademark. By using them over several models, they become a recognisable sign of the brand itself. The body shape, on the other hand, is the product itself, not a "Gibson" signature the way the bottle shape is a Coca-Cola signature. People want a guitar looking like a V the same way they want a drink tasting like Coke or a pair of trousers looking like jeans. That's not a trademark in my understanding. Of course, they really want it to look like the original, and that's where some "copyright" regulation ought to apply.