I don't know of these glitch spots that you speak of....
If they gave the full zombies experience at launch they would have to do the same for weapons and maps of main game. This would give them no reason to fix broken mechanics and release patches .... It is the dlc which pays for the maintenance and upkeep of the game
Without dlc content I am pretty sure they wouldn't spend so much money. Time it energy to even make a zombie mode. Never mind a complete version
--Feel free to add me if you play AW on the X1--