It's always a job to get the word out. If you rely on forums...well, how many visit forums? If you rely on email...again, how many haven't set their email to filter things like msgs from Inno so that they go to the "spam" or "promotions" folder, which they never view? And a lot of people don't visit fb, instagram and all the other places on which they try to get the word out? The only place active players visit is...well, their cities. So "bang for buck" the best advertising is right there where the players are. Personally, I, too, would rather not receive such messages, but they are a business and cost/benefit analysis is their job. They've probably figured out that such a minor annoyance isn't going to drive very many away, while the vast advertising effect of addressing the player base directly will get a LOT more players to try the "new" game, even if a few are annoyed and won't.
It's all in the bottom line.
AJ