They don't have to lower the price, because they already sell it to everyone who wants to play it anyway. I think they could even increase the price and wouldn't lose a lot of customers.
Yeah well, if you already have huge player base, then it is probably no brainer.
But still, imagine a player is looking for a game. He is open to any genre, and doesnt mind trying out new franchise.
Now you have two games, both priced same. if you cut off 25% off the price, what game do you think he is probably going to buy?
And lets not forget, that if boh prices were halved, he would not have to choose. What I mean is, that, for many players, price budget is pretty important, and if they cant afford the game, they are not going to buy it.