First, because it is one of the most common world languages. It is spoken by a very large number of people. Although the scope of distribution and the use of the Russian language declined slightly (because of the aforementioned collapse of the Soviet Union and the resulting consequences), it continues to be one of the five working languages of the United Nations (alongside English, French, Spanish and Chinese). Second, because for some residents of neighbouring countries - citizens of the former Soviet republics, who are now sovereign States, is a must. Some of them come to work in Russia, there are relatives, friends and acquaintances. Russian language knowledge is absolutely necessary for them for work and home, everyday communication. Thirdly, some people abroad have a genuine interest in Russia. For them it is primarily the personification of the rich heritage of Russian classical art. More or less educated, cultural man, wherever he lived, necessarily heard about Tolstoy, Chekhov, Stanislavsky, Tchaikovsky, Prokofiev. Quite naturally the desire to learn the language spoken by these brilliant people, left a bright trace in the world of art.Fourth, globalization has not bypassed and Russia. In Russia there are many branches of foreign firms, companies, new joint ventures. In many cases, foreigners or are headed by such companies or are part of the Directorate. And for the successful production and marketing heads just need to be aware of all Affairs, to communicate with subordinates to understand all of the intricacies. Of course, you can enlist the help of qualified translators, but still, it's not the same. Finally, in fifth, just because Russia, despite all the difficulties experienced by her, was and will be a great power to be reckoned with. It is the largest country in the world, endowed with rich natural resources, possessing the second largest nuclear deterrent capability. She will not allow anyone to speak to him in the language of force. It is necessary to find common ground, a reasonable compromise. And this is very useful to know Russian language.
Why people learn Russian language
Even during Soviet times, the students diligently memorized the rows of Mayakovsky: "I Russian would learn only for the fact that they talked Lenin!". Soviet Union now belongs to history (as mentioned the reason for the interest in the Russian language). Why learn Russian language people for whom it is not native?