Here are a few random thoughts, not put in the best order, I'm afraid, but which will hopefully make sense nonetheless

Although I can only speak for myself, every time I learn a new language, I unvariably feel like I'm getting a step closer to understand the culture, but also the very people who speak it as their native language. Never has it been truer than with Japanese, which is an extreme example of that, as the very structure of the language is a reflect of their social code (levels of politeness and social hierarchy spring to mind). Also, languages are living entities, that evolve through their speakers - in that sense, there are few more appropriate instant photography of a given society

More generally, learning a foreign language is pointless if you're not interested in the culture and people, and if you're really interested in them, you'll probably have the curiosity to learn at least the basics of the language. It's a whole package. Since a given language may have nothing in common with your own, it automatically requires that you leave behind the way you think in your native tongue to "borrow" a different mindset. Getting into a language requires that you get into a set of mind that's different than your own. In that sense, to join your conclusions, it's a very good way to be forced to open a way, not to tolerance, which is a word I strongly dislike (as it implies that there's acceptance, but with a certain degree of reluctance), but to better appreciation of these differences that makes the human race so rich