Armageddon was more or less MK Trilogy for the previous 3 games. When it was being made I don't think they claimed it as anything other than a compilation of the previous 3 games.

To me what was disappointing was that they left out a ton of great backgrounds and features from Deception for no reason.

That's what developers do. They copied the engine from the previous game and tweaked it a little. You don't think developers start from scratch each time do you?

And they ended up breaking it for MKA.
Deception's engine was just fine, yet in Armageddon they added a stupid air combat system which barely worked when I wanted it to, worked when I didn't want it to, and is nothing more than a crappy gimmick. Not to mention some of the combos from Deception were removed or broken.