The promotion of Hindi as the most important language in India is not limited to this Prime Minister or administration. It has a long history, starting from Independence in 1947, when the writers of the Constitution decided that English would slowly be phased out in preference to Hindi [1]. Unsurprisingly, foisting a foreign language on native speakers of Tamil, Telugu, Bengali and other languages was met with fierce resistance. In 1965, this policy was abandoned by the Union Government. Unfortunately, the Hindi speakers who generally dominate government never gave up this crusade. Every now and then they try something that will slightly push the boundaries of what people will tolerate, while not letting the the issue become too large.
Sneaky tactics of the last few years include
* In 2014, Modi decided that all social media accounts run by the government would communicate in Hindi, not English. [2]
* In November 2016, new notes were issued that had numbers in Devanagari for the first time in 69 years since Independence, rather than Arabic numerals. [3]
* In March 2017 mile markers in Tamil Nadu were in English and Tamil. Tamil was replaced by Hindi [3]
But this is not limited to this particular government. Previous governments have taken similar steps. Personal anecdote - I studied in an institution funded by Union government where all signposts were written in English and Tamil. This was replaced across the campus at great cost with signposts written in Hindi, English and Tamil. There was not a single person on that campus who didn't know English or Tamil or both, but the Union govt wanted to send a message anyway. It left a bitter taste in my mouth.
The sad part is that its not just about hurt feelings, as some Hindi speakers might characterise all of this. We are going down the exact same path as Pakistan did post Independence. They tried to force Urdu down the throats of the millions of Bengali speakers living in (then) East Pakistan. "Incentives" to learn Urdu effectively ended up discriminating against the Bengalis, leaving them disenfranchised. Eventually they couldn't take it any longer and declared Independence. I wish we could learn from history rather than repeating the same old mistakes.
[1] - http://www.constitution.org/cons/india/p17351.html (It shall be the duty of the Union to promote the spread of the Hindi language, to develop it so that it may serve as a medium of expression for all the elements of the composite culture of India)
[2] - https://www.nbcnews.com/news/asian-america/india-pm-modi-dem...
[3] - http://indianexpress.com/article/opinion/web-edits/by-pushin...