Interest Check -- No range weapons/spell use in 5e

In a 5e game, that would cripple certain classes/builds. There's a lot of balance considerations in D&D.

If I want to change the feel that much, I'll just play a different system that does what I want by design.

Balance considerations?

*Laughs in martial/caster disparity post mid-game*

100% valid. D&D has always been broken for mid to high levels.

I guess my point was more "why alter those rules so much it could change/break the game or at least certain classes within it, when there's almost definitely a ruleset out there specifically designed to do what you want?"

Is there a fantasy adventure game with no ranged combat? A cursory look found nothing.

Meanwhile, 5e is pretty modular. I once ran a game with only martial classes, and no magic subclasses. It was great. You can rip a lot out to support your game's theme and it still usually works - just look at Shadowdark.

Would a game where you can only use melee-ranged attacks and spells break the game? Maybe. But it might be fun to try, and at worst you will end up casting some spells you never bothered to cast before.

Good luck!

The easiest way to balance martial vs caster disparity:

Double the hit points of every monster. Watch your wizards weep. Drink their tears.

I actually don’t think that would change much. The most effective wizard spells are all about control and so hit points are not as much of an issue as it might seem at first

It will actually bother the martials more as the casters should control, buff or debuff.
If you want to make casters feel useless and unappealing to play, increase monsters saves

If it is just balance, I have found that the optional flanking rules make melee relatively more attractive; no more people saying "the best melee weapon is a hand crossbow."

I find it difficult to believe that 5e's combat is engaging enough to make this interesting. Positioning is already a bit of a nothing with spells in play, aside from your decision where to put your fireball. The resources that melee classes have to change their circumstances on the battlefield are already so sparse when they can carry a crossbow.

Just imagine a combat going for 5 rounds looks like, just on a technical level. How boiled down it is to rolling attack and damage and incrementing down HP. Combat was already like that, and you're interested in removing all the tools players have to inject the scene with any sense of space, place, or dynamism.

The Melee Combat As Function of Setting angle certainly has legs, as Dune proved years ago, but I think a lot of your gameplay and balance issues might be well answered by using a different system. You say you want to use familiar rules, but unfortunately, those rules are doing you a deep, deep disservice. Don't fall victim to the sunk cost fallacy.