Check the MKX forums on Steam and you will see a 50+ (and growing) page of angry fans, many of whom shelled out $80, who cannot play their game right now. It's launch time. It's the culmination of hype time. This is not an MMO. It is Mortal Kombat.
The Stream and Play thing sounds like a good idea, but I've never heard of it being used before. To make the PC version of a huge release your stress test is infuriating. I miss the days of cart/disc and play. Woe to us the gamers who must endure these burgeoning digital days of release date patches, and experimental hybrid weirdness like this.