Hard for the MCC to do any more, other than enforce it at a professional level. They are banned in any game played under MCC laws. We've all played in Pub games with 8 ball overs, no LBW etc. etc. These games aren't played under MCC laws, and the batmakers will just say the bats are made for use in such games. The MCC cannot ban someone for making a cricket bat full stop, it can only outlaw it in any game of cricket it governs.
It is rather like seatbelts, it is the law to wear one (and make cars with them) intended for use on the public road (where the government has authority); however they cannot make you wear a seatbelt if you're driving on a private race track.