Another thing is that people want Sub Zero in the game simply because they want to see how they will design him which is a terrible reason to put him in the game over DC Characters that probably should've been in the game to begin with.
The same can be said about Freddy and Kratos, but those 2 were put in.
I hate the idea of guest characters in fighting games too, but much to my dismay, Freddy was the highest selling DLC, so other people obviously DO want those characters in.
The way I see it, if he's in as DLC, be glad that it's just DLC.
He's not on the main roster.
You don't HAVE to DL Sub-Zero (if he's in) or Scorpion.
You don't have to spend the $5 on him.
Be happy that any guests that appear in Injustice weren't put on the MAIN roster, like Kratos was.
You see, Kratos on the other hand is a good reason to be upset, because a good roster spot that could have gone to someone, like say Rain (who was around during the UMK3 era), was taken up by that piece of shit character.
That's not the case in Injustice.
Main roster spots aren't being sacrificed, in order to bring in these guest characters.
They're purely downloadable and not required at all.
Hell, you never have to see those characters if you don't download them either.
Just wait a couple of weeks until the guest character hype dies down, and you won't see them online.
The same happened with Freddy.
3 weeks after he came out, people went back to using Smoke, Scorpion and Noob Saibot online.