Then have them take a different fighter class because I think the whole point of the champion is that it is more or less passive abilities, nothing for the player to have to track, no having to decide if you want to spend a superiority die now or later, no having to ask if you should fire off a spell or save that spell slot for shield. The champion just gets in there and does his job, he fights, he crits more often, he's a bit more well rounded on physical ability checks. I think the champion is a good subclass for the fighter and it tends to be the subclass I choose for most of my fighter concepts when I'm not making a classic elf fighter/mage.
I'm not necessarily saying that passive abilities are not good or don't have potential. Or, if I did in fact say those things, let me correct that here (not going to go through my previous posts or worry about semantics). I think that abilities that are active or require player agency to activate are perhaps "sexier," but when done right passive abilities offer just as much potential for fun. I just think that the defining characteristic of the Champion, the expanded critical hit range, can be so finicky for several reasons.
First, while it increases the chances of a critical happening, it may never really be noticed because it is still sooooo tied up in how the dice roll. If I go multiple combats without a critical, then for me personally, it feels like I got robbed. Or if I DO score a critical, but it was on a natural 20, then it's like "Oh, well that would have happened anyways."
Second, critical hits are generally just getting to reroll the weapon dice. Don't get me wrong, rolling dice is fun (obviously) but it's not as fun when you score that critical hit and then roll a 1 or 2 on the critical hit dice.
Now, all of a sudden the thing that defines your class pick has so many ways to fail you and let you down by either not landing a critical, landing a critical but it being a normal natural 20 (slightly less exciting I would say), and having a underwhelming damage roll on the critical. You've invested class levels for a chance of a chance to have something exciting happen.
Passive abilities can be fun and well executed. As I mentioned above, fewer people complain about the Thief vs Assassin/Arcane Trickster. But the Champion's passive abilities don't really
feel like abilities at all. At least, that is my perception.