There are so many reasons for why children should learn a new language.
One reason why children should learn a new language is that it is easier. As you get older, it becomes harder to learn a new language. This is because when you are younger you only need to learn the words and what they relate to. However, when you are older you need to learn the language to be grammatically correct. This gives you twice as much to learn.
It is also easier for children to learn languages as they are not afraid. When learning they are not afraid to sound like idiots. It is also possible to make learning a new language fun for children. You can incorporate games. This becomes more difficult as you get older, making it feel more like a chore.
You can still learn as an adult, but you will need more dedication.