I think there are just very view people who will buy a 60$ game for offline bot matches.
Not to mention the fact that it would shift players away from other competitors like Call of Duty. Why ?
Because in recent years Call of Duty has been an absolutely terrible experience on PC because of the "always online" garbage that BattleNet enforces. If the servers are overwhelmed for any reason you can't even play the campaign.
A lot of PC players are also very unhappy with the fact that in CoD on console bot matches are available completely offline while on PC the slightest connection interruption kicks you out of the game with nothing working.
I can't think of a better opportunity to show Activision how it's done and just how much value offlline bots can bring.
Like others already said, having offline bots can be better than having a campaign --> much better replay value.
