I don't really understand this viewpoint, the show became massively about Ash at the end for the same reason Ash/Paul and the Chimchar storyline took up the bulk of DP. The only difference of course is Dawn got a lot of screentime compared to Serena, but then you have Brock who was basically pointless in DP whereas Bonnie had fun moments throughout the series and a great role in the Team Flare arc, and Clemont got pretty decent focus for a male companion in the series. The show also wasn't any more "edgy" than the darker parts of DP such as Paul abusing Chimchar or Hunter J, or Dawn's depression streak. While XY did glorify Ash a lot, it more or less made sense given what point we are in his journey, it's why so many people thought he could possibly win the league based on how he was portrayed.It was awful. Actually, XYZ was awful. XY wasn't too bad. It was too edgy and there felt no continuation to the previous Saga's. This is mainly seen through Ash's identity, where he slowly became the archetype to every negative characterization of a shohen protagonist. By the final gym the show had become this massive Ash circle jerk and the other characters were left in the shadows. If we could consider a percentage of time dedicated towards each character in the show since it's beginning, Ash was focused on far more in XY than even in the indigo plateau. Seriously, everything revolved around him and it was tiring. Then there is the league, which was only saved by it's animation. However, the handling of it was far worse than Best Wishes. The pacing was awful and the lack of reserves was upsetting.
The only positive to the show was it's animation and Serena and Ash's relationship. The rest was forgettable and the whole show was completely over-hyped. Sinnoh is still the best Pokemon series to date, and by a large margin too.
XY seems to be remembered just fine given we're already 3 years after it ended. Bonnie and Clemont are still very popular and liked characters, Serena is depending on how much people liked her crush, and Ash's XY pokemon are very popular. In fact there's often a debate between DP/XY which was the best saga, with Kanto / OS and AG somewhere in the middle, then SM and BW. Unless the Gen 8 saga turns out to be really good and amazing, XY will probably stand out the most of every saga of the 2010's.But no one will remember Kalos.