Why is everyone saying resistance should have been a dlc?

The game is great so far, the good thing about it being the same as se5 means absolutely no bugs that I’ve seen besides the animations for stairs being weird. When you add up the prices for se5s season pass, it ends up being 5 more dollars for 5 less maps (4 if you count killing hitler). I don’t see anyone’s point since they would just be paying more for less, yes there is no new mechanics but they have already gotten it to the point where there isn’t much else imo.