I'm pretty sympathetic to the developer point of view, but really, changing the rules of "the game" after it's in progress seems like a fair reason to be unhappy.

If you'd been able to buy power with cash from the start, fair enough. Anyone who played knew what they were getting into, it's firmly their fault if the game is unfair to non-paying members.

But, starting out with an even playing field and then making it uneven after people have invested time and energy into the game is at very least pretty frustrating. It makes people feel like they've been tricked, because suddenly they're no longer playing the game they thought they were playing.

Even though it sounds like the p2w aspect of the game is pretty minor now, it's kind of a trust thing. They've added non-cosmetic microtransactions once, so they could do it again and again, until the game is basically Clash of Clans Crush Saga. There's really no reason to believe it won't happen.

At that point, you no longer even have the option of continuing to play the game you once enjoyed and invested a lot of time in - it's just gone, and nothing will get it back.

Of course, given that (if I remember correctly) Agar has no real persistent gameplay then it's not as bad as it normally is when this happens. I think people are sensitive because usually p2w games have long-term progress/goals are heavily disrupted by the p2w additions, which isn't the case here.

People give devs way, way, way too much crap for wanting to be paid for their time in general. Still, it's pretty frustrating when something unexpectedly goes p2w. For example, I've spent hundreds of dollars on my favorite games, but none of them offer power for money. If they suddenly started, I'd feel like my favorite games were taken from me and I'd feel tricked.