Nojima and Uematsu formed their own companies because they don't want to go to corporate meetings - they want to create.
Actually, the reason Uematsu left was because SE moved from Meguro to Shinjuku. Why did they move? Because Wada listened to a fortune teller who told him there was better luck in Shinjuku. What an idiot Wada is (assuming the story is true).

A Day in the Life of Final Fantasy's Nobuo Uematsu from 1UP.com
A Day in the Life of Final Fantasy's Nobuo Uematsu from 1UP.com