Better than Adventure! Forum

The engine enhancements that BTA make are genuinely amazing, especially controller support. Is it possible to disable the modded content to just keep the engine improvements?

While BTA provides some gamerules to disable some things, most additions cannot be disabled.
You can either play the mod and not interact with the additions too much via the classic world type,
or, play the mod as it is.
I'm sure you'll enjoy it as most bta additions aren't very jarring and fit within the game quite well.
If you don't fancy either for those options you can try Beta Recobbled
as I've heard that mod sticks more closely to beta while making its own improvements to the game.

This would make sense if BTA was a mod for beta 1.7.3 that fixes bugs and adds a couple of small additions, but since BTA is so gigantic in its feature list that it doesnt make the most amount of sense to add the ability to remove it, you can always just play on the Beta 1.7.3 preset but that still allows some stuff that you probably dont want, you can always use a mod/modpack like beta unleashed or Back 2 beta or the many other modpacks that exist for the purpose of fixing bugs and improving performance, if you want controller support back2beta does have it iirc but it doesnt support steam input sadly

You can't really separate "engine improvements" from "modded content"