It's important. For me at least, it keeps me sane(-er) lol. Recently started learning python for a sublime text plugin :)
It's important to develop the areas you don't know. There's a famous quote by Albert Einstein - "The definition of insanity - doing the same thing over and over again and expecting different results". So if we want to become better developers we can't really do it by not pushing and expanding our horizons and understandings.