I already see the comments overflowing with misconceptions:
-Sora, as much as I love him (I actually voted for him in the ballot), would NOT be a Square Enix rep - Disney COMPLETELY OWN all of the copyrights to the original KH characters, as stated by Tetsuya Nomura (Square Enix legend) in the KH Ultimania. So Sora and Cloud don't really effect each other as reps, since they would represent two different companies, even if the two both feature in the same series and share the same creator.
-Cloud has appeared in a few Nintendo games. Not as a major role in any of them really, but he is not without a presence on Nintendo. Off the top of my head, he's in:
- Final Fantasy Tactics on the GBA
- Kingdom Hearts: Chain of Memories on the GBA
- Kingdom Hearts - Re: coded on the DS
- Final Fantasy Theatyrhythm and it's sequel on 3DS
- The upcoming Final Fantasy Explorers on 3DS
That being said, I was very surprised myself, and I would have preferred someone like Cecil Harvey or Black Mage as a SE rep since they have more relevance to Nintendo. But I am fine with Cloud, and he's pretty much here because FFVII is what made RPGs mainstream, and they are a big thing on Nintendo. I've always wanted an SE rep as I feel they are huge Nintendo collaborators and I like a lot of their games.
Cloud does advertise for Sony more than anything, kinda like what people say about Snake. However, Cloud is unarguably on par with the 3rd parties we already have. He's the mascot of Square Enix and he helped make what is now a huge game genre become mainstream. He's a welcome addition that I can much more easily get excited for than a C-list, one dimensional Nintendo character like K. Rool or Daisy or something.