As great as it would be to get Mother 3 in the West it just isn't in the cards. The game is a localization nightmare, especially with the current climate around topics of sexual preferences, race, gender, fascism, and sexual assault. It would be a huge controversy to release that game today.
Should it be? No. The game is harmless. But that is the reality of the world we live in.
As I understand it Nintendo looked into porting this game back during the Wii U/3DS era and eventually scrapped the plans when it became apparent how it would be received in America.