The games had to feel "fresh" and allow players to feel as if it's Generation 1.
Obviously, the anime went the same direction.
While they didn't really "reboot" the series, they made it simply fresh for a new, younger audience.
XY is supposed to be an All-Stars thing, with the game developers putting in ideas that would appeal to ANYONE. For example, Mega Evolution was added for older players that grew up with the series who got bored with the same damn mechanic over and over again.
The XY series does the same thing. Yes it does feel a lot like Advanced Generation, but the truth is, they combined every aspects of the previous anime series, like adding the "freshness" they tried with Best Wishes, with the exception of Ash.
tl;dr TPCi knows what they're doing.
