So for fighting games, character passes are a good thing(overall).
If you bought SF4 at launch and continued to play the game throughout it’s life, you ended up buying the same game multiple times. This was essentially a few characters and a balance patch(had new mechanics as well). This the fragmented the player base a lot, so if you were playing the base game you couldn’t play with someone on the latest version.
Street Fighter 5 however, switched to character passes and even being able to unlock characters with in-game currency(difficult if you came to the game later but possible). This means everyone got the balance patches and major system updates, so the player base stayed as a single entity.
For a niche genre, this is significantly better than multiple purchases of the same game, and allows for a game to get more updates over a longer time.
However I do wish they kept in more unlockable content like costumes, colours and stages.
Specific to Street Fighter 6 though, they have a battlepass(which is not good, but isn’t terrible either) which the free version gave/gives out a bunch of character rental tokens, so you can play with DLC characters you haven’t purchased.