If I could give a controversial opinion here, the show's problems did not start with BW, as many claim, but actually started with AG and continued on all the way through to the end of BW. They repeated storylines and ideas ad nauseum, to the point the show became devoid of creativity. Needless to say, I do not want a return to those days and am delighted the show has tried new ideas.
To elaborate on why I think AG-BW were the problem, it's mostly to do with Ash's characterisation. It's often said he had consistent character progression up until the end of DP, but I find this to be a misconception. He had a character arc throughout OS, but noticeably regressed in different places throughout AG and DP, with him ultimately learning the lessons he had already been taught.
In AG, Ash grew arrogant after his seventh badge, and had to be put in his place by Drake so he could learn to remain focused. But one of the key parts of his original character arc was learning to leave his ego at the door and focus on the needs of his Pokemon, which was symbolised by his changing relationship with Charizard. Why did he need to learn this lesson again?
After the Battle Frontier, Ash lost to Gary so he could learn that there are still challenges to be overcome, but this exact thing had already happened at the end of the Orange Islands arc. Why did he need to be taught this again?
Then, we get to the start of DP. At this point, you'd think Ash would be over shouting matches with people, right? Well, DP thought otherwise. Ash was very confrontational with both Dawn and Paul in those early episode, far removed the emotional maturity he was supposed to have gained by that point.
I feel a lot of this is ignored because Ash's skill as a trainer was relatively consistent during that period, which gave this impression he was steadily progressing. It was only when BW messed with that progression that people started to complain about resets and soft-reboots, when those complaints were about six years too late.
Pokemon during that time was, effectively, caught in a loop of telling the same story over and over. It had no idea what to do with Ash after his initial arc had concluded, so they just made him have the same experiences. Ultimately, this made the show dull and predictable.
XY broke this cycle by actually doing something with Ash's character. He was both skilled and wiser, and adopted a role of guiding others rather than being guided himself. They realised at this point that Ash was now a flat character with little scope for change, and so used him as a catalyst for growth in others. SM (and this will blow people's mind) was a natural progression of that, putting Ash in a slower paced environment where his love for life itself could shine through. People often point out how Ash's lack of drive or focus in SM was a sign of regression, but I thought it was the complete opposite. These were signs Ash had matured as a person and had a broader view of the world than just Pokemon battles.
And this is just Ash. If Pokemon wasn't prepared to try new things, they'd still be using recycled stock footage in XY when its director was pushing for something better. We wouldn't have got a character as a genuine love interest, or a renewed focus on action scenes, or a drastic improvement in animation style and quality, or storylines about death and parents neglecting their children, or Ash actually being allowed to succeed. There are misses along the way, but this is much preferable to me than just more of the same.