This isn't just content people want and Blizz doesn't want to give because it wouldn't be profitable, it's an entire half of the game that was advertised since announcement. A lot of people got the game with the assumption it was coming. It wouldn't be "live service" if they'd included it from day one like they promised. It would only get looped into that because the "new content" should have been in there from the start. It's Blizz reaping the benefits of an empty promise but wanting none of the blame when people call them out.
Absolutely, but even after release fans got told it was coming. I checked out of OW after the PvE debacle in OW1 so this doesn't surprise me, but a lot of people still thought Blizz was going to hold up their end of the bargain, even if it was a little late. So they got it just to play PvP until it came out which, as we can see, it probably never will.
A lot of people got the game with the assumption it was coming.
Do you mean they bought Overwatch 1, with the anticipation that at some point after the release of Overwatch 2, they would add PvE? Because Overwatch 2 was free to play from the start. The only thing that you could "pre-order" was a pack that gave some cosemtics, some premium currency, and the first battlepass. At that point PvE was something they were still planning to add at some point but still had no date, so you could only use those bonuses for the PvP.