Why should Boxing be different from almost every other sport?

Throughout sport, the athlete are breaking new ground improving all the time playing at a higher standard but for some reason boxing is not. Over the last 100 years the 100m sprint times have tumbled, people have lifted far more, jumped longer and higher, swam faster. Physically man has improved, obviously this is down to advancements in modern training and nutrition. But it seem like sacrilege to even thing along these lines in boxing. Why don't we think that today's boxers hit harder, faster and take better shot. Why has the advancements that other sports have made are not happening in boxing. Perhaps they are happening but we just don't like to accept it. It not only the physical advancements that we have witnessed, football has probably has it greatest player now in Lionel Messi with Ronaldo not too far behind, with Barcelona considered the greatest ever side. Snooker and darts are playing at a standard far above past generations. Men's tennis has 3 of the greatest players ever to pick up a racket playing now. There are about 5 times as many people on the planet now that there was 100 years ago, more countries involved in boxing now, more boxing clubs, so why is it so hard to accept that are sport is at its top of its game. If you don't believe this then explain what makes boxing different from almost every other major sport?