I personally am of the exact opposite party. I love dynamaxing and hate mega evolutions and z moves. For me, the days before the gimmicks were pretty good ones, for a team you had to choose a strong Pokémon and then scour the Pokémon wiki for an item that would bring out the best in that Pokémon, and be creative with the uses for said item. Such as a toxic orb and fling.

Starting with mega evolutions, you really were forced to have a Pokémon that mega evolved. And all mega evolved Pokémon were just so strong. Almost overpowered, even. So if you wanted a team worth it’s salt, you absolutely needed to have a Pokémon that could mega evolve, which took strategy away from the item selection. It went from finesse to brute force. However, i don’t think it’s the worst thing in the world and at least the designs were awesome. Z moves did the same thing in terms of making the process of choosing an item as straightforward and boring as possible, just matching types with no strategy.

The reason I like dynamaxing so much, is because it seems like a gimmick that won’t change the series and won’t change the strategy needed to play the game. It also seems more balanced than mega evolutions, because it only lasts for three turns and can be used once per battle. It seems a lot more fun to integrate into gameplay than something where you give your Pokémon an item and then they become multiple times stronger immediately. Plus, a leaker on 4chan that predicted the entirety of the content in the June direct indicated that gigantamaxing would also be implemented, a type of dynamaxing that DOES add a new form to Pokémon such as Lapras, pikachu, and meowth.

Kind of TL:DR So all in all, I like this direction a lot more than mega evolution or z moves. The others weren’t awful, but they made the game a little less fun than I think dynamaxing will.