1) Half or more!? well count them.. it's third or less. How can you be sure he doesn't? even so, it's not his call but Nintendo's. KHIII on Switch, I'd like to see that happening. I don't think it's possible any time soon.
2) Does KH or DQ really need an introduction after all these years? isn't it better to drive sales of a slow sales game instead, that's already on the system and exclusive to it?
3) Whom are those people, and who is more popular? Sora lives in Sonyville. I'm not a TWEWY fan and I'd love to have Neku over Sora or Slime.
1)
Sony ..................................
Nintendo
Kingdom Hearts................Chain of Memories
Kingdom Hearts II.............358/2 Days
Birth by Sleep......................Dream Drop Distance
Birth by Sleep 0.5...............reCoded*
*Technically a remake/re-release...but it didn't release for phones in the West, so I'm counting it.
As you can see, without counting remakes/re-releases, exactly half of the Kingdom Hearts series has been on Nintendo consoles..and if they do end up porting the HD Remixes to Switch like I somewhat expect they will, then they'll have exactly the same amount of the series as one another.
2) No, they don't, but neither do Sonic, Mega Man, Pac-Man, Metal Gear, Street Fighter, or Final Fantasy. The only 3rd Party that arguably needed the promotion is Bayonetta, but at this point its half-Nintendo. I just don't think Square-Enix nor Nintendo would want to promote a lesser known, less selling series as DLC then one that they know for a fact will sell gangbusters. The point of these DLC characters is to make money and more people will buy a well known property then a lesser known one.
3) Pretty much anyone that wants a different Square-Enix series* or doesn't quite know TWEWY..you can't tell me you can't see people being angry by his inclusion..this fanbase gets angry at just about anyone's inclusion or exclusion.. Please stop saying 'Sonyville' or implying inferred ownership to Sony simply due to how many/how important they are to a different system, literally the same things can be said about Snake and Cloud yet they're in and, honestly, more of their titles have been on Sony systems then Nintendo's then Sora's have. Sakurai does. not. care about console 'allegiance' but rather their importance to gaming as a whole, remember that even if Nintendo chose candidates, Sakurai chose who from those candidates became DLC.
*Note: Kingdom Hearts is NOT a Square-Enix series, it belongs to Disney, SE would be a consultant at best.