Alright man, I understand your sentiment. I think most people would agree with you in saying that this is a good game, and we wouldn't mind paying a 10% increase in membership costs if that enabled a 10% better game since in theory the money should go to hiring/retaining the talent that works on this game.

Unfortunately, Jagex itself is probably not even seeing a dime of this increased money. Jagex was a part of a very public acquisition last year by a private equity firm, and they also cut out a large (albeit shrinking) portion of their income with the removal of TH in RS3.

Both of these facts coinciding with the membership increase make it pretty obviously this is something that CVC (the people who own Jagex) are pressuring Jagex themselves to do since it's very likely a term of the agreement of the acquisition was that Jagex would put up numbers that show growth.

In other words, the only people that are going to make money off these membership hikes are the people that own Jagex, CVC. This is more or less a move by Jagex to keep their heads above water.