I don't recall saying this would be useless I think I said its more trouble than its worth. If you want to do FULL 3D with animated meshes and other things like that it would not be worth trying to bend the codebase to do what you want it to do, it would be better to go use an engine meant to do 3D if you want 3D not bend a 2D engine into making a 3D game.
Making a plugin that could import simple static meshes has its value but you also have to think about how big are these meshes going to get before we start to see slow down. the 3d box now is 12 tris and Im not sure how many you can have on screen before you see slow down but even things like barrels and crates take up any where from 100-300 quads which means 200 - 600 tris the equivalent of having 50 3d boxes on screen in one object. making a Higher poly model 1000-2000 quads(2000-4000 tris) is equivalent to 166- 333 3d boxes on screen. In one object. That is a lot of polys to deal with