Character customization is a thing people have been wanting since before X & Y's release. It adds to the immersion of the game, and at the very least gives you something extra to do--when you reach a new location with a clothing shop, you take extra time to go in and customize yourself, and you're encouraged to save money to buy the clothes you want.
This may sound a bit harsh but I feel it's the truth: character customization is the only worthwhile (non-battle mechanic) feature to retain from X & Y. And because it's something that benefits the games' immersion in addition to being a fan-favorite feature, it would be very, very awful if they weren't brought back as a series staple.
Honestly, the number of people here saying it probably won't come back because "look at Pokémon following you, that never came back," and other similar things, is really quite alarming. I mean, I get where they're coming from (I could argue that Pokémon following you, while fun, isn't as immersive of a feature as customizing your avatar, but I'll save that for later), but it just goes to show how...little hopes people have for these games. Come on, guys! I know what it's like--you don't want to get your hopes up because that's how you get let-down. But these are the 20th anniversary titles. They skipped "Z" for this! It's not wrong of you to expect that they keep highly-demanded features.
The trailer did say these games would "bring all the others together," so maybe this feature you think will remain Kalos-exclusive will actually be included after all!
