English includes a lot more words than most people use regularly. I imagine that's the same in any language. Just expanding one's working vocabulary in one's native language would probably be quite helpful for thinking and expressing oneself more fluently—not that learning another language isn't valuable.
I'm told that English will create words for where other language create grammar. (which can be anything, from a new tense to prefixes to other things I cannot imagine because I don't know the language)
