Kuma as character was surrounded with lots of mystery for such a long time and now we are starting to learn more and more information about him, it is kind of dumb for some people to think that his backstory is going to be irrelevant and not important when we have yet to see his backstory.
I do think his backstory will involve more than just Kuma's sad past, also Kuma is a character that has been built up for such a long time and now we are in a arc in which we are getting more focus on his character.
Kuma is a former warlord, a revolutionary, the former king of the Sorbet Kingdom, the father of Jewelry Bonney, and he is from a special race.
Yeah who cares about his backstory.
Fuck those people, I actually want to see his backstory.