As opposed to what? There's no other good way to control multiple characters simultaneously outside these two systems.
Even controlling one person, if they were going to do an ARPG, they would've continued the Dark Alliance series. A FPP game is waaaaay out of Larian's wheelhouse and the engine they use probably won't support it. A TPP OTS D&D game is already a thing and it's completely dead.
So BG3 will be a battle royale roguelite MOBA card game? Lets get real, it's going to be RTwP or TB isometric top down.