I am always curious as to this, and in truth, a little bit hesitant. Why mess with a model that works? They made the boardgames and a skirmish game and some choose your own adventure books, and all of them are meh. My hesitancy comes from the possible influence those things have over the direction of the game. That could just be me, and I own that fully.
OK, so 4e is at least straddling the line, you can play it more-or-less as a classic D&D with the GM decreeing all of the story elements and players follow along, add color, and maybe choose between 'branches', or pick one of a menu of possible story arcs. Or you can play it with the players deciding what quests to originate, directing most of the flow of the game through choices like class, race, pp, ed, theme, background, etc. Some people, enough to rouse WotC to action, weren't happy with that.
So, I don't understand why we cannot, as a product of its own, reconstruct that mode of play in 5e and have that option back. It doesn't do anything to hurt precious classic 5e! Heck, you may well find things you would want to mix into your game in there. I'm really just talking about a set of classes, some variant and optional/additional rules and clarifications and such which facilitate the sort of gaming that people like myself,
@pemerton, etc. did with 4e and enjoyed. 4e was a very good selling game, overall, and so clearly there could be a market for that, right?
Certainly it might or might not make business sense to WotC, what do I know? It surely should be no issue for you or anyone else. It cannot, literally like logically not possible, spoil what you've got now. I mean, everyone tells me that I can still play 4e, and they're right! So I am not seeing what the issue would be...