For anyone who has never checked out the interviews section at the mortal kombat conquest site, http://mkc.netcessorhost.com/, i recommend you do. here are two little pearls well worth everyone's attention:
Co producer Dean Barnes:
Why MKC ended?
Warner Bros. Distribution and TNT were unable to sustain market interest in the product for another season.

James Cappe, executive story consultant:
The good guys died and Shao Kahn won in the last episode. What do you say to that? Whose decision was that? And from Spike: "I believe that 'Vengeance' was an excellent season finale, but a terrible series finale. Well, I guess that is not the writers fault or anyone else's since they had a second season planned."
We wanted to come up with a cool season finale. We had every intention of returning and bringing back most of the characters, though we hadn't worked out how that would happen. I remember that we were going to have Omegis involved in some sort of resurrection. When the series was cancelled we never had the chance. Yes, it's a terrible series finale.