That's assuming that limiting player choice is a bad thing. There's such a thing as the paradox of choice - too many options and and people are confused and less satisfied with the final result.
I would assume that most people that play D&D are casual players, especially when it comes to character builds. Make a couple of choices, pick between some simple options and go have fun playing with the group. Besides don't most people fit a certain archetype when it comes to their career? I'm a computer programmer, not a nuclear scientist pro football player astronaut who dabbles in artificial intelligence and bio-engineering in my spare time.
There is more to constraint than people realize. The reason people get excited about combos and loopholes is because of some constraints!
Many things are exciting because they are found within some boundaries and may have been hard to identify at first. There is a tension between choices and boundaries. That is what makes this a game instead of merely ‘let’s pretend.’
I only say this to point out the fact that unfettered player choice is not necessarily ideal. If people say ‘you mean you don’t think choice is good?!’ My response is that of course it is: within some boundaries.
In a way, boundaries are what separates one game from another. Likewise assumptions are what we hang our shared fiction on.
the selective changes our world makes to assumptions and boundaries are what makes a creation novel and unique, much as playing against type does for some characters.
no one argues for a game so bogged down by boundaries that it’s not creative. No one is arguing for story hour. But the dial to set how far one way we go is set to different number by different people.
in my opinion you have to be the most careful with constraints. It is what makes this game ‘D&D’ with classes and races.
you can knock some of those things down but I think that is best done in unique campaign settings which are interesting because they deviate from baseline.
as stated earlier, you have to have some archetypes in order to show uniqueness. As I said earlier, if you want to color outside of the lines, you first have to have lines.