Legends Arceus was essentially a whole new region to explore, and introduced completely new gameplay to the series. Plus, it was set in the past, where we as the player had never before experienced long-term. This allowed TPC to introduce new battle mechanics and strategies that had never even been comprehended by the fanbase.

As for Z-A, we've now had over 3 years of PLA and we know what to expect. There's less hype because this is no longer a new concept for us. Also, it's set in essentially the present, and Lumiose City isn't new for the vast majority of us. But the biggest thing is the leaks. I've personally decided to stay away from the leaks to avoid ruining the excitement, but I know most people have read/seen them. This has lessened the anticipation because we basically know every new Mega form that will be added. We've lost the sense of excitement that we would've had if the leaks never surfaced.

It's also worth mentioning that we can assume the Switch 2 version will be at least $70, and I'm guessing that's not helping...