The aim to learn a language is not to learn a language. The aim to learn a language is to be able to use that language to get things done.

This should be the core of language learning, not learning the language for the sake of learning it. Only learning a language for the sake of learning it doesn't get you very far, and it's hard to stay motivated. If you have a different motive for learning a language, such as to improve your communication skills, develop intercultural awareness, or perhaps to learn new things about yourself, then it makes it much easier to learn when the going gets tough, and with as tough an endeavour as learning a language, that tends to happen sooner rather than later. Hence the reason why languages shouldn't be learned for the sake of learning them.

This also makes an argument for students to start learning second languages at a later age, as they will have more awareness of its usefulness, and will be closer to using it in real life situations.