I just finished watching it again.
Yeah, people who were born past the 90's will have different standards by now, but IMO it was the simplicity of the storytelling and like what
Tfritz mentioned, the movie does a lot by having very little. I'm not sure if it's because of Paul W.S. Anderson's frugality with the direction, or Jogn Tobias and Ed Boon's intervention(?), but it was for the longest while the movie adaptation that felt truest to the source material
and atmosphere.
Also with regards to its lack of gore: It manages to side-step it with Scorpion's death and Reptile's in that "it's not really considered R-rated if it's not human" variety. It still has a lot of impalement, and oddly-enough Shang Tsung's "soul-sucking" scenes sort of show flesh being ripped from muscle and bone...before promptly "sucking" those as well (I guess it's suppose to represent the entirety of their souls somehow?). I guess it kept the feel of violence happening which was why many felt like giving it a pass in that department. And as other said, its more of a rounding up the plot of the first two games.
tl;dr - MOOOOORTAAAAAAAAL KOMBAAAAAAAAAAAAAAAAAT