Firstly, as a disclaimer, I'm one of those 'Chinese children who learn English at a young age' which leanor mentioned. Nonetheless, I think there are many advantages offered by the Chinese languages that are not available in others. I will elaborate below.
Firstly, Chinese morphology makes it very easy to guess the meanings of words. As an analytic language, there is little inflection or derivation that goes on, and compounding between lexical morphemes is the most common type of morphology. Thus, if you learn a few basic morphemes, new words are very easy to learn and remember. For example, 'computer' is 'calculate-machine' or 'electricity-brain' depending on the region.
Moreover, the language is very flexible. POS changes are usually not marked as the grammatical categories are very flexible. For example, you can use an adjective as the subject or object of a sentence without derivation. (Classical Chinese went even further - in fact, you can say 'He knifed the pig' instead of 'He killed the pig with a knife'.) There are no tense, case, mood, etc. markings in Chinese, either, although function words can be used to express these concepts. Thus you have a choice of not expressing many things, a flexibility not allowed in most IE languages, and to an even lesser extent to tribal languages with vigorous morphological rules.
Chinese is only useful when you are traveling to Taiwan, China, some parts of Mongolia and other countries.
English on the other hand is more or less the Standard International Language. At least 52 have english as official language, 30 more at least have people that can speak english and Most countries use english in the tourism industry (aviation and foreign business as someone mentioned). The majority of the world can understand basic english (unlike Chinese).
Although Chinese might seem like one of the most useful languages because it is one of the most spoken languages in the world, the majority of people that speak it live in Asia. In the rest of the world, Chinese is spoken very little, while languages like Spanish and English are generally more useful and easier to learn,
People have spent years, devoting weeks of hard effort into getting the best possible usage of their language. My mum has a degree in English, the mere concept of that suddenly being considered trivial is horrendous to me. And she would not be the only one. Sure, Chinese is a fine language. But English is here to stay.
Chinese is only required if you travel to China, otherwise English is the most useful language and having global understadging and usage. English speaking people you can find even in China, english is largely used as business language, aviation industry and many bilingual nation are speaking english. Chineese lanugauge may take another 50 years to become popular.
As a software engineer who lived in China for 2 years thus picked up some of the language (inevitably) I was also under the impression initially it would be an extremely useful language to learn. I couldn't have been more wrong. Firstly, English is the most useful language to know because it's the most business orientated language and most of the high paying careers in the world (in any country) will usually require knowledge of this language - comparatively at least.
Chinese is only useful if you want to travel China, inside China it's mandatory to pass your CET-4/6 to get a university degree. So every young professional in China knows English to some degree. This means that there are many translators from chinese-english and indeed chinese-towhateverlanguage. The market rate for these translators are pretty poor compared to say German-Japanese. Partly because Chinese mainland citizens are paid pretty low wages and partly because so many people speak a combination of Chinese and another language.
I can only say Chinese is useful in China, Taiwan and some of the Asian countries (although no more so than English!). I would really only recommend learning it if you plan to stay in China for a large period of time. Also take into consideration it's one of the harder languages to learn. Not worth the effort.
While Chinese is a good language to know, English is by far a much more important language. It is spoken by 67 countries in every continent. Chinese and Mandarin are only spoken in a few countries. There is a reason a lot Chinese children learn English at a young age.