My guesses of the logic in the legal stuff is that fter minecraft is done , that there will be expansion pakcs , large updates , sort of like maps for any modern FPS , that you could optionally buy , but if you'd be an Alhpa player would be free. That is what I understood when beta came out.
No one would buy the expansions because people could just recreate them as mods.
It would also cause major incompatibility between players and servers.
At the moment, you have to find a server that fits your needs, isn't already full, isn't forgeted up by community, and you have to either find one that's not whitelisted, or try to get on the whitelist. Let's not add the "do you have the right expansions" to the equation.
Poll