Why is D&D still Medieval?

[Scots Dragon]

As Twain said, there's three types of lies - lies, damned lies, and statistics.

That said, I don't see a particular agenda in these cases to drive any kind of manipulation.

Notably, it's easy to see why it's the case, especially for beginning players.

Human is the easiest race to play. It's approximately average, and you kinda know how to act like a human from your own life. There aren't always that many stat adjustments or extra abilities to write down, at most you get a bonus feat or skill point.

Fighter is the easiest class to play. You have a sword, you hit things with the sword. You don't have to rely on sneaking around, keeping track of spells, or anything else.

And since it's what you start with, it's what you become used to.

Now, I'm sure an optimiser can say something about battle masters being more complicated than that, or how it's actually really hard to build things properly in third edition, but I'd point out that most parties don't optimise so strongly, and I'd also point out that a beginning player is likely also part of a beginning gaming group where nobody else really knows how anything works either.