Your cynicism is partially justified, but not fully. In economics there exists a concept called "normal profit" the gist of which I'm not going to explain but you need to look up. In short if profits from in-game ads start driving total profit of the game company up to an attractive level new competitors will be drawn into this industry and competition will drive prices down. This is a pretty fundamental concept of supply and demand and would work wonderfully in this situation...
The gamer's problem, however, is going to be that they really don't care about the subscription price enough that they'd be willing to play something other than their favourite game because the subscription price is higher than a competing game they don't enjoy as much. In this case they're pretty much stuck. They have the ability to vote with their dollars but they won't. No sympathy from me.
Video games are not commodities and as such if you really want to play the really hot game you can't expect them to fight tooth and nail to shave a few percent off the price to pass on to you. They don't need to.