If Satoshi disclosed his identity, there could be some difference like people knowing his country, religion and other differences. Some people may start to conclude that bitcoin is becoming to be slightly centralized or centralized like altcoins. But as people do not know about Satoshi, it makes it more decentralized from the beginning while others bitcoin developers also want to keep it like this.
It's true, but don't you think that Bitcoin become substantive enough not to be hurted even by it's creator? If it was from the very beginning then definitely knowing of Satoshi's identity changed a lot but as for now... I think most would say thanks and that's all. I don't think he can still influence on Bitcoin even if he can prove his identity. Bitcoin IMO doesn't depend on Satoshi anymore, it is grown up.