Because that's how it was designed? Gat out of Hell was intended to be a small standalone expansion as a bonus to the remaster of SR4 on X1 and PS4, all of which were developed by the studio High Voltage.
Development started in August 2017, and we confirmed it being in development a little over year ago or so. You may want to double check your math on this one.
Except that we can't. As you already know, asset release and timing is all controlled by Marketing. You know, like we've explained over and over and over... and over...
It takes someone incredibly determined to keep insisting they are entitled to something after being told repeatedly that we do not have control over timing decisions. Keep on shouting your demands and shaking your fist at the heavens, good sir.
While we created the original game, we were not involved with the remaster which was solely done by Sperasoft. Deep Silver support should be able to assist:
support.deepsilver.com/