It doesn't matter if it's intuitive. Lots of intuitive things are false. Further, the more you think about it, the less intuitive it is. I believe that second

It doesn't matter if it's intuitive. Lots of intuitive things are false. Further, the more you think about it, the less intuitive it is. I believe that second languages, completely unstratified on other factors, is correlated with "better brains" by some metric. I do not believe that the statement that this is causal, or totally uniform. Could it not be that better brains seek out new languages? Could it be that learning a language is healthy for some part of the population and not others? For a trivial example, is learning a fifth language really worth your time? Is it possible that people who learn a new language would do absolutely nothing with that time otherwise? As for my own thoughts, learning a new natural language is extraordinarily boring. There are no problems to solve, it's just memorization and exercise. It takes a tremendous capacity to deal with boredom to learn a new language, and the tremendous capacity to deal with boredom does not strike me as uniformly good, though it does strike me as probably being correlated with higher average intelligence.