While some feel it was the Mortal Kombat: Annihilation movie, Mortal Kombat vs. DC Universe is popularly touted as the lowest point for the franchise – at least in terms of video games. The prototype IP soup tried to do something new with popular characters going head to head, but never really got a good reception.
The biggest issue was that with the introduction of DC and Warner Bros, MK's iconic gore had to be dialed down. Batman, after all, cannot be split into two by Kung Lao's hat. However, while the game itself signaled the fatality of the Mortal Kombat franchise, its core formula is what resurrected it to become NetherRealm Studio and the reboot we've come to adore.
MK vs DC wasn’t awful. If reception for that game made mk9 possible then hopefully the failures of MK11 can make some good changes as well. It’s time to get rid of variations, they had a good run but ended up a mess.
I think MK 9 did.
In fact I remember being bummed that this was a T rated MK game and just dismissed it. MK 9 was when I actually stood back and said, "They're back!". Still think that game is fantastic.