Pokemon Co. explains why they went with DLC expansions for Pokemon Sword & Shield, and how Dynamax Adventures came to be

Pokemon fans have become conditioned to think that new Pokemon series entries will be quickly followed by an updated release that adds some new features and mechanics. That's no longer the case, as Pokemon Co. has gone the DLC route with Pokemon Sword and Shield. Instead of a new game based off Sword and Shield, Pokemon fans have gotten two DLC packs for the game. In an interview with Game Informer, Pokemon Co. explained why they chose this path.

There was an element of apprehension in moving to a downloadable model, but we were confident that players would enjoy exploring the new environments, uncovering new storylines, and meeting new human characters and Pokémon in both The Isle of Armor and The Crown Tundra. With past titles, players generally had to collect and raise their Pokémon completely from scratch, so with a DLC we thought players would enjoy being able to use their favorite Pokémon right out of the gate.

Crown Tundra, the latest DLC for Pokemon Sword and Shield, introduces a new Dynamax Adventures mechanic. Pokemon Co. also explained why they implemented this feature.

The idea for Dynamax Adventures started with the team wanting to introduce new elements to Max Raid Battles. We think Dynamax Adventures was the perfect way to achieve this. We wanted to change the way in which Legendary Pokémon are captured in our games. Some of the Legendary Pokémon that appear in Dynamax Adventures differ between Pokémon Sword and Pokémon Shield. Only by joining up with players using a different version will you have a chance to catch them as well.