As a company, you want communities like Gamepress and TSR. The more communities you have, the more interest there is in the game and the more players / $.
It is also a pretty easy way for Niantic to get the "pulse" of the community. I'm sure they read the forums even though they may not act on every single comment / piece of feedback.
A big part of what keeps people interested and playing the game is having communities like Gamepress (at least it is for me as it gives me a one-stop shop to ask questions, interact with other users, and learn about the details / nuances of the game).