Worldbuilding only matters if the Mechanics Support the World

Sword-Coast D&D is so dominant that it's not only the assumed setting for all D&D campaigns, it has become the default setting for essentially all western fantasy. When someone wants to break out of the mold they need to open their story with a rape or a brutal beheading; get that Game of Thrones energy on display, otherwise everyone is going to start looking around for kobolds. 

This isn't a bad thing; I like the Forgotten Realms, I think. It's a fun place full of adventure and bright colors and wizards and curses. I like fantasy. I love it, in fact. 

But I do sometimes want a different kind of story. One that doesn't slot into the same grooves as thousands of other games. We live in a world of imagination and I want to use it. So every now and then I'll bang together a new world, one utterly distinct from the Sword Coast, with a history and culture and its own monsters and cities and cosmology. And I'll drop my players into it, and--

Look, you know what happens. The same things. The fighter fights, the wizard casts his spells, they talk to people, they seek treasure, they make a balanced party. They do the same stuff, just in a different place.

I think this bothers some worldbuilders and leads to them starting to preach. "No, there's no monarchy in this land," they'll say after you roll a 9 on your knowledge check and they decide yes, absolutely sure, you know a little bit, and it is the following 6 paragraphs speech about a republican revolution led by Githyanki slaves; when you finish your players are texting and nodding, 4% more dead than before. Preaching is the enemy. Unless you're Homer, you're probably not cut out for it. 

But then how do you get the players to appreciate this world? They aren't interacting with it! They're just...playing D&D; it's as if they're in Waterdeep! 

It's one thing to create a new and specific setting; but if the players are given the exact same tools, they're probably going to keep using them in the same way. Why shouldn't they? They don't know the world and they sure don't want to study your dissertation; that's not why anyone plays an RPG. They want to be part of a world, not listen to someone talk about it. So how can you make them be part of it?

Take away their options. 

Well, you can add some, if you like. But I'd recommend stripping out; D&D is a hugely broad game. It might not be GURPS, whatever that is, but it allows for nearly any stock fantasy cliche. And that's the problem: you don't want a stock fantasy cliche; you want extensions of your world. So to do that: change the options. Outlaw classes, limit gear, change the game. Force them to realize they're not playing in Faerun! 

Obviously you should let them know beforehand; some people really want to play a Kenku. They're my enemy, these people, but I will grant them the right to happiness; provided they stay out of my group. Let them know this campaign has limits. Once the familiar tools are out of reach, they'll start grasping for new ones. And then they'll start gripping your world. And then you don't need to preach--they'll learn the world just by being part of it.