People hate it because they put in huge amounts of time into their accounts only to have it wiped out from power creep and microtransactions. Jagex completely reversed their stance on critical game design policy multiple times: "No old skills going to level 120" (which was promised after the release of dungeoneering), "We don't want player's real life status to affect their game progress" (removed from the anti RWT rule after the release of buyable squeel of fortune spins), "No more new tradeable discontinued items" (Fish mask, black santa, christmas tree hat, etc added to squeel/treasure hunter).
They are monetizing the game by holding players' previous achievements hostage. Worst of all, however, was the EoC update which was met with universal disgust during beta, yet they continued to develop it anyways. Instead of mindless passive combat where you click and wait, they changed it to mindless active combat where you click, spam number keys, and wait.