Maxperson
Morkus from Orkus
Not simple enough. Even the "simple" totem Barbarian has 3 choices to make from among 3 options each time. 18 different combinations compared to the Champion's 0. It's not terribly complex, but I've played with a number of players who don't want to have to make decisions like that. They just want to write down what they get at a level and move on. The game is in their words, supposed to be relaxing fun, not involve work. D&D is an escape for them and they don't want to have to worry about character creation choices beyond race and class. The Berserker is often more maniacal and mindless in battle than players want. I've seen very few who have wanted to play one over the years due to the fluff and/or mechanics of it.Barbar Smash.
Plus, as I said, there is no good reason to change(or get rid of) the Champion. It's there for them, not you. You can pick from the other Fighter options or campaign for a new subclass that fits your needs.