I agree on the flavor but I think part of it is that it's a lot of hassle and just doesn't look as appealing as breast meat. There's a higher chance of biting into gristle/something hard, the meat can be "slimy", and I find that at chains that do "fried chicken", at least, they do a generally poorer job of breading the meat. It's not crunchy and battered like a "chicken tender". Thighs are a different matter since you can pick/scrape off the bone with a knife and fork, but they're also larger so the batter to chicken ratio is sub-optimal.

Wings are tolerated because they're small and predictable, but I've been seeing the rise of "boneless wings" too. People generally don't have a problem with the thighs and legs of the chicken if it's served differently or just as "chicken" in another product. But on the bone it's messy.