They’re entirely right. If they paid for it to not change anything except when polled, then the company broke their promise. They should now vote with their wallet and leave.
Because while they are right that they didn’t get what they were promised, the company that makes the game is also entirely right with doing whatever the fuck they want with the game. If they want to break their promise, that’s entirely up to them.
I’m pretty sure the company didn’t enter a contractual agreement with the playerbase to never make unpolled changes. So the only thing you can do is voice your discontent and leave. Which is exactly what seems like it’s happening and what should happen.
Now what I would strongly disagree with is your assessment of “most of the playerbase is pretty right leaning” and upset with it. How do you know this? Did you personally poll/study all, or an accurately representative sample of RuneScape players, ensuring an unbiased evaluation of the data? I suspect not. I suspect what has happened, again, is the vocal minority doing what they do, being vocal and a minority. There’s a loud outcry from, just guessing, 5% of the players, while the silent 95% like it or don’t care and just continue on.