This answer is very simple and complicated. Why I am saying this because,Hindi is one the official languages and language of majority in India. It is the 4th most spoken language in the world that means it has more speakers than many official languages of UN i.e. French, Russian and Arabic.
One who knows Hindi can easily understand Urdu also, this also increase the speakers of Hindi language.Most of the non Hindi speaking Indians understand Hindi but very few Hindi speaking Indians know any other official language of India which is 22 in number.Every major university of the world has Hindi department.There could be many points in favor, but I think major points has covered and if anybody knows others please put at the comments I will try to add them also.
And now we will discuss the complicated part despite being many points are in favor of Hindi then why Hindi still not an official language of UN and even why it is not the national language of India also? Because majority of the Indians speak another language other than Hindi, so they do not prefer Hindi to their mother tongue.If Hindi become an official language of UN, It will be an economic burden on UN, lots of translation and other works will take time till now, India is not facing any problem because UN has English as an official language which is also an official language of India.
If Hindi become a language of UN then it will great in India’s favor which shows the world’s that India also has some footprints in the development of world, it will increase India’s soft power. All Indians should support this.
Originally published at http://quora.com.