User blog comment:XLC-OR-66/The "Character Select Screen" Rumor/@comment-24092382-20140425085422/@comment-4696205-20140425222108

DarKingdomHearts has his points, but which including that, there's the most biggest reason they can't put Mii in SSB4. I'm not quite sure if this is happening in the US, but I pretty much heard this info from many Japanese sites as it really happened a lot in there.

Just like DarKingdomHearts said, people can create their Mii's look like certain celebrity and fictional characters, or even other real-life people such as their family and friends, or even non-relative person like classmates and co-workers. But, they may create those as if they mostly HATE them, and want to create their Miis for insults, threats, slander, or even voodooism reasons. They may use them in private but some can actually bring them in public and use them to let other players beat them up as the creator watches it for fun, sadism way. This may reference to the points that Sakurai illegalized for the online mode back in Direct, to avoid many problems caused by players.

Plus there may be possibilities that people around the world use Miis only than any other characters, which may lose the meaning and purpose of Smash Bros.