It's funny, to me, how something in your language doesn't occur to you. For example, in English, we say good bye which is a way of saying God be with you. If one believes in God, that's a pretty nice thing to say. I remember pointing out to my Japanese friends, that a term for tomorrow, ashita 明日, which means tomorrow, can also mean Bright Day, or clear day, which struck me as rather poetic, in the sense that no matter what today was, tomorrow will be a bright day. On the other hand, a common word for thank you arigatou, basically translates as life is hard. 有難う. And my wife and other native Japanese speakers realize it subconsciously, but they never thought about it, till I brought it up.
I'm sure that every language has similar optimistic and pessimistic meanings, and other deep meanings that lie behind common phrases, that the native speaker doesn't realize because they hear it so often that if there's sentiment behind its origin, it's become meaningless.