I’m not too sure about that, since the new raycasting API allows rays to hit parts that don’t collide with Default. This was only a problem with the old API.
Besides, this suggestion doesn’t have anything to do with raycasting, just studio tools. Games shouldn’t be affected if this bug is addressed.
I guess, but something to keep in mind is that this won’t work if you plan on sharing your work (as a free model w/e etc.) Moreover, this would mean that you’d have to set every part in the game to a separate collision group that behaves exactly like default incl. players, and that’s just really tedious.