Fesin: Why would you do this as a developer?
(a) because you don't know that the software you're working with automatically adopts to the language of the OS?
(b) because you think it's no big deal to add such a command line, as you expect all of your customers to be tech geeks like yourself (or maybe you aren't even aware that there are less tech-savvy people in the world, or if you are, maybe you're arrogant and think such people don't deserve to play your game)?
(c) because you're too busy or too lazy and don't feel like adding graphical in-game options menus?
Choose one. ;)
(In any case, I agree that it doesn't make a professional impression, and seeing that Bastion is a highly acclaimed and popular game, and now even published by Warner Brothers, I don't think it should get away with such excuses anymore.)