So MFL is not an important skill to acquire because we don't really need to speak other languages, because everyone speaks English. Riiiiight. I think Bruffin has just illustrated why MFL is so undervalued in UK schools.
Obviously you can get by without speaking another language. You can get by without a knowledge of history, of literature, or of classical civilisation for that matter. I don't have any practical application for my o-level Geography knowledge of escarpments and terminal moraines, or all that business about the periodic table and atomic bonds. And I doubt many people other than maths teachers regularly need to solve simultaneous equations in their daily lives. So we could probably scratch all those sections of the secondary curriculum which don't come in handy for adding up your supermarket bill, working out your tax return, filling in your census form and earning enough to keep a roof over your head. 
If you're going to look at it in purely utilitarian, Gradgrind terms, then most of the stuff in the secondary school syllabus is not really that useful for most people most of the time, apart from maybe ICT and food tech. But school syllabuses aren't restricted to supplying people with skills that they will use in their daily lives, they are structured to provide a broad introductory knowledge and insight into a range of academic disciplines which will give them a starting-point for discovering what they're good at and what they enjoy, and also give them at least a passing experience of the vast body of human experience and learning. People don't just learn a MFL so that they can order a beer at a bar in Spain, because the Spanish barman almost certainly speaks English. They learn a language in order to get an insight into how language works on a wider level than just English, and also to give them the opportunity to gain deeper insight into other cultures, countries and literatures. And if we want to add a utilitarian angle to it, it bears mentioning that UK businesses are snapping up people who can add a decent competence in another language to their skillset, because it enables them to communicate with businesses in other countries on a completely different level than if they expect all forriners to just man up and speak English.
Sigh. Obviously there are some dc who are struggling so much with basic maths and English that there is a good argument for exempting them from the wider reaches of the full curriculum. But for everybody else, we rightly assume that they should be given the opportunity to learn a full range of subjects which provide at least the basics of an all-round education, of which having some familiarity with another language is an integral part.