I agree entirely. I'd actually love to see Ninten as an alt for Ness when Lucas releases.
Here, they look like they might be a little too similar, but:
In other pictures of the model besides that one which is floating around (which I think is a "cleaned" version of it), Ninten's shirt is noticeably baby blue rather than dark blue, which would add enough contrast when combined with his shoe and sock color and his hat facing the other way. Heck, they could include the scarf he wears in
this Japanese Mother 1 commercial if they wanted him even more distinct.
I know it won't happen in all likelihood, but a pack with Lucas, a Ninten costume, and Magicant being ported to Wii U (and Onett to 3DS) with a graphical upgrade would really make my day.