Well, if the people end up complaining about the game, most of it is based on the replay value of the game. Usually complaints are about the modes or the storyline itself, not on the language. The language option may keep them playing for awhile longer, however, I don't think it will save the game from being bashed in the end.

Yes, there are many pros to this language option, but the question again has to do with profit. None of these pros matter anyway if it has a negative effect on profit earnings.