The use of Skinner box-style game mechanics and other aspects of behavioural psychology have been on the rise in game design for years, to the point where they've been almost universally embraced by most major publishers and entire business models have been built around them.
I attribute the success of my own CivClicker to the application of those principles, but I've always been resistant to monetising. I've had a lot of people ask me why I made CivClicker donationware, rather than (as with developer Naquatic's mobile port CivCrafter) opting for a microtransaction-supported model. My answer is this: my design goal was to see if I could apply the theory, not to exploit people for extra cash.
Just how exploitative these design principles can be never really hit home until reading this article. As game designers we have a duty to make our games accessible, and a positive experience for the player. In the future I'm going to be very careful with my choice of mechanics; to use the insights from behavioural psychology to design better games, but also remain responsible and be mindful of the unintended consequences of those choices.
The examples are many, and they raise the ethical issue of using psychology to take advantage of the disabled. If even those without a neurological impairment can fall prey to behavioral psychology and deliberately predatory game design, what hope do the rest of us have?