>>26507943That applies to many new concepts in Pokemon. They introduce something novel, its faults become apparent over time, and they rework that concept for something new.
Shaymin's time-and-item based transformation was expanded upon by Hoopa.
Meloetta's mid-battle transformation was followed up by Mega Evolution.
Keldeo automatically transforms if it knows Secret Sword, much like Rayquayza needs Dragon Ascent to Mega Evolve.
This also applies to items. Soul Dew is a good example - it was overpowered, but limited. The following gen we got similar, lesser items for all mons to use. Also Choice Band, which was introduced a generation prior to Scarf and Specs.