I think for better or worse, it was the point most fans realised Ash was likely never going to win a league.
I think the writers knew that too, hence trying to take a different course with Ash's approach so it's not just a repetition of the same Shaggy Dog Story.
I think as many were upset about the fact that XY looked like it might be a game changer and a little often sneakily hyped itself up as being such. Then Ash lost the league, Greninja left, Serena parted ways, hell even some BW changers got abolished, Team Rocket reset completely into stagnant incompetents who interrupted nearly every episode, etc. It felt like even more a kick in the nads when they saw SM previews and Ash at face value was almost a completely different character. It was like XY could have been omitted from the timeline altogether and it wouldn't make a difference.
SM IS altering the formula and direction, but we don't know if that will have any affect on the next series. Like XY, everything could just revert to as it was a decade ago.