So, when you see Inbox by Gmail being even more intrusive with ads than regular Gmail, you can raise your arms in the air and declare that you were right all along -- "I told you so!"
I feel like a person who wrote a novel and based one of my characters on an old woman who worked at the corner store, but yet a literary critic reads the "hidden meaning of the text" and insists the woman really represents my mother. And then when it's pointed out that the character is based on a real person who is not my mother and the critic is simply wrong, it's claimed the woman must secretly represent my relationship with my mother anyway.
You're basically asserting that years of product meetings, in which ads are not discussed, and which the only concerns are how to improve user workflow and usability in email, in which we do countless user studies getting feedback from experiments, and then making changes in the system so that people tell us it's working better for them, all of this really is an engineering and product team being manipulated by strategic decision makers.
And while we think what we're really doing and working on is making it easier to manage your mailbox and get at information quicker, we don't realize we're playing right into the hands of a Machiavellian plan by the executives/board to use those same mechanisms for even more intrusive ads, and they haven't let us in on the secret.
Or, maybe we're just trying to make the mail experience better so that people don't get sick of gmail or mail altogether, and go off and use WhatsApp, social network "mail", or some other communication mechanism not ruined by a deluge of noise. Maybe we're concerned that if we don't make things better, users will go elsewhere.
Or maybe, after 10 years, we just thought it was time to give gmail a refresh as it was getting long in the tooth.
All are better and more plausible explanations than the idea that this is a monetization plan for gmail. I personally don't believe mail can ever be monetized effectively like that. Personally, I think mail ads are pretty ineffective and not huge revenue generators.
The reasons for impuning the motives of Google here are political and consequentialist, not about user experience or software quality.
It's about the consequences of having a 3rd party organize and filter your communications according to it's own incentives rather than yours, it's a discussion about power.
It's about the politics of service providers putting themselves in the middle of p2p communication in order to surveil them (to monetize the software/service with ads in this case, although of course the NSA is happily given a copy).
It's not about thinking people at Google are mustache twirling villians or bizdev douches who ruin things by plastering ads on them, it's about the crappy direction that well-meaning people are taking the internet.