Every IB event could be the perfect occasion for f2p players to finally get a set but instead it's useless because it's literally impossible to reach enough materials to get any piece.
IB sets have very high prices and there aren't other ways to get them exept buying from cashing players so allowing f2p to get them at least in events is the bare minimum.
Obviously the idea is not to just give a set for free but to give it after doing tasks