The Champion suck and is unsatisfactory because the mechanics were designed for a style of playstyle that a huge chunk of the community doesn't play.Considering they are also very popular in terms of actual usage, it's pretty clearly more complicated than that.
And no, @Minigiant it's not because they built those options for a demo that doesn't play the game and has been replaced by a totally different demo. It's because they didn't execute their goals well with some PHB options, so people play them because they love the archetype or because they want the implied playstyle, and then the option doesn't deliver.
The Champion is what people want. It just also sucks, so it gets played and also scores very poorly on satisfaction. In case it was about to come up, I'll head off the "Champion is free" counter arguments that always come up. Adam Bradford confirmed that the DDB class and subclass rankings don't change when viewing only people who have purchased the PHB and other books on DDB. Champion gets played a lot because a lot of people want to play it. That's it.
So, any "solutions" to the Champion that either cut it or gut it, are non starters.
That's the whole issue.
If you play the way 5e was designed, there is no Fighter or Wizard problem.
The issue is if you don't play that way, the Champion Fighter, Berserker Barbarian, Rangerr, Sorcerer, Warlock, and Monk all kinda suck.
You see this in other games "You are trying to play Pathfinder like 5e. Play the way the game the correct way and then the casters are fun" I've read and heard many times.
People want the Champion fighter's image. 46% of 5e don't want the Champion fighter's mechanics. Because the Champion's mechanics was designed for 54% of the community. Because 46 of the community don't play the style or lack the DM that the Champion was made for.