Completely agree with you one this, I'm the same.
Yes and no, without the voices the game is probably incredibly dull and boring so yeah, maybe they'll get the game cheaper but it'll also be a disappointment to them.
While what you says about the price on Steam is true I still believe that this is not a very honest solution, when I saw G-Senjou no Maou on steam I almost bought it right away without looking too much because I really love the game and now I still feel a little bit tricked. (Not saying I won't buy it, but still ...)