Crits have nothing to do with the specifics of the monster or the combat. They exist because people get excited when the die comes up 20, and the game wants to lean into that excitement.That is a fair point, but it seems more like an argument against having crits in general than about not changing them, because people still get that same intuition when they have a really big to-hit against someone with low ac.
This is why they got rid of the confirmation roll from 3E. The confirmation roll was a logical design mechanically; it guaranteed that you didn't get a higher proportion of crits against high-AC monsters. But it overlooked the fact that crits weren't a "logical" design in the first place. Crits are about yelling and cheering when that sweet sweet 20 comes up.
If you have to do math or roll again to know if you got a crit, you lose the thrill and now it's just making the damage roll more complicated for no reason.