Perhaps you have intimate knowledge of that change that I don’t, so I can’t really speak to the reasoning behind the change.
However my understanding was that AnimateableBody2D was specifically added to 4.0 to affect other bodies in its path when moved, whereas StaticBody2D does not. Hence making it good for platforms.
So I guess you’re right, it can be used for projectiles that do not impact the movement of anything it hits. But I feel like the OP is still going to be writing a lot of physics code when hopefully RigidBody2D gives most, if not all of what’s needed for free.