These additional decks expand your strategic options and provide more cards for your collection
-sigh- Commanders emphasis on color identity in deckbuilding has successfully kept Krrik, Son of Yawgmoth from being a huge problem in the format as a whole, but its still a powerhouse that should be removed or countered on sight against decks with a large or exclusive emphasis on black, as 4 mana can easily become as much as 16, more if life gain enters the equation
There's also the question of whether Friede, in particular, will be keeping his Charizard as a Dark Tera Type
Ragavan FTW: These are the best cards in Modern Horizons 2 The flipside of this is Tovolar, the Midnight Scourge - a 4/4 that still lets you draw cards, but also allows you to pay X, one Red, and one Green, to give a Wolf or Werewolf you control +X/+0 and Trample until the end of the turn
Alongside the limited supply and extremely high demand, there are plenty of reasons why Pokmon cards make for excellent investments