Another, closely related, case is when you love the culture the language gives you access to. Learning a language without interesting books/movies/tv shows behind it will most probably be a chore.
What language doesn't have interesting items of culture behind it?
Russia no doubt has interesting items of culture as well, but I am not exposed to them at all and therefore have no desire to learn Russian.
Some people likely find any items of culture interesting. I'm not one of those people, and I suspect most around me aren't either, or we'd all know a lot more languages.
Languages often have neat features, but that isn't enough for me to prioritize learning one above other things.