I would say its mostly because of his personality. Its so boring and false that it annoys most people.
I agree with his style having a lot, if not everything to do with it. He is a skilled fighter, no doubt. Mayweather was a boring fighter and arrogant but was able to put people in the seats and come out the pocket to pay for his fights. So I don't think it's those things that keep Ward from being a huge or bigger draw. I just think he doesn't have a pleasing style for the casual fan. He isn't brash like Hamed was but, Hamed put guys to sleep, so being smug or arrogant isn't it. I think if Ward had one punch ko power and conducted himself in the same manner he would be a bigger draw no doubt. Arrogance and smugness has nothing to do with it.