1.) You'll be exposed to a very different grammar, one that can change your way of thinking. I believe Chinese won't do that nearly as much if you are native English speaker. Not sure about Korea.
2.) You'll learn Kanji, which will give you an advantage when you want to learn Chinese. You will even be able to grasp quite a chunk of written text when you know Kanji in and out and travel to China.
2.) You'll learn Kanji, which will give you an advantage when you want to learn Chinese. You will even be able to grasp quite a chunk of written text when you know Kanji in and out and travel to China.