Not really for mechanical reasons, health packs exist and Mercy players are prone to gluing themselves to Bastion's backside because that's what the game incentivises; it's because of how troubling the lore implications are.
The actual reason I don't play OW2 isn't the kit changes for any OW1 character in particular, though, it's because I don't want to learn how to counter the [checks the wiki] ten characters, that's honestly lower than I expected but still a lot, that they've added since then.
I'm also grouchy about 5v5, but apparently they're thinking of adding a 6v6 mode on a more permanent basis, whereas the new characters aren't going anywhere