The problem with making the scene between Scorpion and Sub-Zero both your trailer and your opening scene, is that this movie feels like a bait-and-switch. Past that scene Sub-Zero becomes a tertiary character, Scorpion is a plot device, and we end up following some new character that we're given next to no reason to actually care about.
The story is poorly constructed, much of the acting is stiff, and the dialogue frequently falls flat. Most of the fight scenes were good, but that's all the movie really has to bank on.
Scorpion, Sub-Zero, Kano, and Jax are the best parts of the movie.
You can't build a whole movie on good fight scenes alone. You need a coherent story and convincing characters to hold it together. If I want to watch a Mortal Kombat movie, I'll just rewatch the 1995 version or the 7 minute intro to this movie. If I want to watch violent fights and fatalities, I'll look up cutscenes from the games.