It is illegal, but I do not see it being bad for consumers. If anything it seems that it could be good if it has been done legally from Nintendo instead of being a leak.
This information was actually leaked from a subcontractor, not from Nintendo themselves. It's not clear if Nintendo ever had access to it in its entirety or even knew about it. The subcontractor company is also quite obscure, it's hard to tell how they ended up developing this stuff.