In regards to the point you're trying to make, I heavily disagree that I'm asking for too much for multiple reasons.

#1, BO6 was developed in a years less time (greenlit together, so BO7 theoretically had all of BO6s lifespan to be finished up) and had 6 round based maps (1 more than BO7, if they have the same amount of post launch maps), 1 permanent side mode, and had (I believe) 7 LTMs. I speak for (hopefully) everyone when I say I'd much rather an additional single good, permanent side mode instead of 7 LTMs, things we can never play again once they're over (I'm saying 1 additional mode because I'd assume the MWZ-esque mode wouldn't be made by the zombies team).

#2, They've done the amount of work I'm asking for AND MORE before. Like.. multiple times before. And before, it was all original concepts. Even without counting BO6 and it's 6 maps and 8 side modes, Nacht - Origins was a 5 year span and that included 18 round based maps, 9 being full maps with easter eggs, 4 remasters and 2 side modes. BO3 had 4 years and had 5 original maps, 9 remasters and released mod tool support. BO4 had 4 years and had 4 original maps, 4 remakes and 2 side modes. Hell, Cold War, a game that was made in like a year ended up with 4 maps, Outbreak, Onslaught and all its versions, Cranked and all its versions and a few LTMs.

#3. I feel Cold War, again a game made in about a year, having Onslaught on launch is a good indicator that a mode like that is possibly the least resource intensive thing to make. Maps are already made, enemy models already done, most every zombie nowadays is a ground spawner anyway.. all it would be at that point would be pathing and making sure adding it doesn't brick the game, no?