Why didn't we switch to 4e/5e?

[Knaight]

That's not a 5th edition problem. That's a d20 problem. If it's really a problem, you could always go 3d6 instead, and figure out a workaround for crits and crit-range-extenders.

It's a 5e problem. The problem isn't the d20 on its own, it's the combination of the d20 with some pretty piddly modifiers. If you swap proficiency out with proficiency dice, where each skill is 1d20+att+prof(d6), suddenly the issue with proficient skills largely goes away, and it creates a new variable that lets you represent variation in skills beyond proficient or not. Expanding the range 3e style also cuts out the problem in 5e.

I don't particularly like the 1d20 for skills, but it's bounded accuracy as implemented that broke the system. It was clearly built for the combat system first, where it works just fine - and where multiple dice rolls are expected, thus mitigating swinginess of the d20 and making the modifiers count for. It was then lazily exported to the skill system, at which point it started causing problems.

I mean, I could just as easily say that most 3.5 mechanics are overcomplicated to the point of being unusable, and that any player who wants to play something that's not a [your desired point of balance here] is going to have a hard time making it work.

You can and you should. This board could use more pushback to the idea that rules heavy games aren't just preferred by people, but inherently and objectively better than lighter games. It could also use some pushback to the idea that the complexity of rules you favor in an RPG is actually a meaningful indicator of mathematical skill, let alone general intelligence.