You want to lock away special content for every player because you don't want to see it in your game. That's selfish.
MK does not need guest characters to stand, but it does benefit massively from it. What generated more buzz? Kratos or Rain? And the whole shitstorm of hate was an isolated incident. The amount of people who didn't give a shit and just wanted the characters vastly outnumber the people who were crying about it here.
No.
It's a solution for both types of people.
If you want a guest character and I don't then why not have the best of both worlds?
Being an unlockable or having a mandatory compatibility pack works best.
At the very least, a patch update with the compatibility added in.
Rain and Kratos both got TONS buzz for different reasons.
Rain got lots of buzz, due to fans wanting him in and complaining that he wasn't.
Rain was an actual UMK3 character that was missing from the main roster and LOTS people were pissed off.
Kratos got lots of buzz, due to people not wanting him on the main roster, and that he got priority over Rain.
Also, the Freddy and Scorpion rage wasn't just and isolated incident.
Obviously, you were wearing horse vision blinkers.
As I stated above, it was pretty much everywhere that people were pissed off, not just here.