Indians simply do not and did not need English as a uniting force. India throughout its 7000+ year old history has remained united as one unified nation under the leadership of good rulers. So, to say that India needs English to unite itself is beyond absurd and beyond ridiculous. And on top of that, to say that Indians have little in common with each other is like being divorced from reality. Indians have everything in common with one another although some cultural expressions and customs might be different. INDIANS SHARE THE SAME CULTURAL, LINGUISTIC, ETHNIC, RACIAL, AND EMOTIONAL CHARACTERISTICS WITH ONE ANOTHER. So, how on Earth can somebody say that Indians have a little common with each other?
Many Hindi-speaking shows are more dominant and resonate with most Indians all over India. The bottom line is that the majority of people can understand Hindi in the South Asian region of India, Pakistan, Nepal, and Bangladesh be it spoken or written. Bengalis can pick-up Hindi very fast if given education from the getgo, and being taught to show love and respect for it. Now that being said, we do need strict laws backed up with good governance to teach people (since they are kids) time and again that there should be one language which unites people from all over India, which must be a language that originated from India, and is dominant in many states of India (like Himachal Pradesh, Bihar, Rajastan, Haryana, Delhi, Uttar Pradesh, Madhya Pradesh, Chattisgarh, Jharkhand, and even Uttrakhand). Even in a major province like Maharashtra, the script of Marathi is similar to that of Hindi (i.E. Both use Devanagari script). Even in Nepal, Nepali is written in Devanagari script. And Urdu on the other hand is like sister language of Hindi. So Hindi obviously takes more precedence over other smaller Indian languages spoken in just their own individual states rather than multiple states.
Now think about it regionally, Pakistanis can understand Hindi but verbally. Nepalis can understand Hindi in its written form although they may not be very fluent when it comes down to writing. But, they can become fluent in Hindi in less than 2 years or so if given Hindi education from grade/class 1. On the other hand, Punjabi, Gujarati, and Bengali is very close relative of Hindi in the sense that a lot of words are very similar. Sound-wise or verbally, all the Indian languages share a lot of common words. South Indian languages have a lot of words with similar meanings as Hindi too.
If you look at the whole thing regionally (keeping Pakistan, Bangladesh, and Nepal in mind), it makes far more sense to have Hindi as a nationally and regionally dominant language be it spoken or written (i.E Devanagari script also used in Maharashtra and Nepal). Hindi-speaking states are multiple whereas Tamil, Kannada, Telugu, Malayalam, Gujarati, Oriya etc. Speaking states are just one.
Teaching foreign languages opens doors in employment, and let's face it, anybody that's had to call customer service has seen proof that knowledge of English creates jobs in India. It's a very poor country, there's nothing to be gained from constricting the employment opportunities people living there may be able to obtain.
It's a UNITING force in India. Besides being Indian, the Indian people have little in common with each other. One could walk to the village next door and hear them speaking a different language. Most of them speak good English, if you get rid of the language, you remove one of the few things that connect them all.