Roxas and Xion almost didn't return for Kingdom Hearts 3, but Nomura let them have a happy ending to please the fans.
One of the most tragic parts of Kingdom Hearts is the fate of Roxas and Xion. Xion, a puppet made out of Sora's memories, and Roxas, Sora's Nobody who is used by the Organisation for his Keyblade, both suffer a lot throughout Kingdom Hearts, which led fans to want to see a happy conclusion for them in Kingdom Hearts 3. Thankfully, that actually ended up happening, with the pair looking happy alongside Axel in Twilight Town by the end of the game.
That apparently wasn't always the case, however. In an interview with Famitsu regarding Kingdom Hearts 4, Nomura talked about the ending of Kingdom Hearts 3 and how he changed around some of the plot points to keep fans happy. The biggest example of Nomura changing something to please fans can be seen with Roxas and Xion's story in Kingdom Hearts 3, which Nomura admits to having decided thanks to fans.
As translated by AitaiKuji, Nomura said, "Regarding Roxas and Xion reappearing Kingdom Hearts 3, I was hesitant up until the very end about bringing them back, and even had a story route where they would not return. However, since I knew that the fans would want to see these characters again, I went with the route where they would return.”
In the same interview, Nomura mentions another, much less drastic, example of how he listens to the fanbase to decide certain elements within Kingdom Hearts. After being asked why Riku got a haircut in Dream Drop Distance, he said, "In KH2, a lot of players said, 'cut Riku’s hair!' So I listened and gave him a haircut. If you ask me who exactly cut his hair, I’d say it was from the wishes of the players". That still doesn't explain the random Heartless haircut he got in Kingdom Hearts 3, but we'll give it a pass.