Well first off i would do away with mw because that has been a shit division pretty much since Pavlik stop fighting and consider most people are that size never understood why that divisions talent level was so underwhelming. As for why people would watch heavyweight well that pretty simple the hw weight champ can kick everyone ass which appeals to people. The smaller weights some of them are just midgets compared to most people hence no one cares. The heavyweights will never look as good because one punch can end you and when your that big it is hard to look flawless the HW division only had few great eras 70's and 90's rest of it is a great fighter and the gatekeepers pretty much.