I know, Mother was in the same spot as Metroid and DK in that respect, that they only got a second rep. by the Third smash game, but honestly, who else is there really to add from either series? Ridley, and Dixie Kong(Or Cranky Kong, maybe Funky but i doubt it) and that's about it. Mother has a few more candidates than that (Jeff and Masked Man, and Kumatora for example), but im getting off topic.
I get that Mother isn't popular or anything, but still, i think they deserve at least one rep. mentioned at this point, given that it's only a month until the JP release. Literally Mother, Wario, and IC are the only franchises that havent had a rep. to represent them in Smash 4 yet, and we all know Wario is going to come back. Besides, Earthbound VC is still one of the Top 10 Best selling Wii U games for a reason, people like it. Not to mention, Unlike Metroid and DK, They got their second reps. showed to return in Smash 4 relatively quickly, but all the fans are worried that Lucas is going to get cut due to his status as a "Partial clone", or a complete clone to the eyes of those who only see his special moves. Well that, and the fact that Mother just isn't that popular in Japan that much anymore, and that while support is high in the U.S., NOA basically ignores the series save for the VC release. :\ Like i said, i get that Mother isn't popular, but that doesn't mean the fans are going to be demanding for at least one rep. revealed at this point given how things with Nintendo and Mother have been rocky in the past.