Why poet Bharathiyar is called a Mahakavi Bharatiyar is because he was in parts all of the following poets rolled into one.
A great poet with a wide range of topics and poetic style was at once fluid, flamboyant and flexible to flow with the tone and tenor of the topic.
Many people could not tune into his frequencies of ideas.
He was Robert Browning (poetry known for dramatic monologues)
Robert Burns (poems known for rebellion against orthodox religion and its morality)
Wordsworth (portrayal of nature, emotionalism and highlighting individualism)
T. S. Eliot (satirical, prophetic and winding into philosophical meditation),
P.B. Shelley (bold radical views on social and political aspects of life),
John Keats (natural imagery with unbridled aesthetic sensuality),
Alexander Pope (in terms some mock- heroic poems alluding to didactic observations of hyper consumptions)
William Blake (abstract poetry),
John Dryden ( his intense devotional poems are as in Religio Liaci unleashing passion - sometimes romance-and reason to process truth),
S.T. Coleridge (on conveying nationalistic pride in common conversational vocabulary to ensure it had a reach)
And the icing on the cake was that he was a connoisseur of classical music that he could compose even wordy abstract poetry into great songs.
It is sad that he has not been as much appreciated as one wish he ought to have been, compared to many other poets. It was because he was not fully understood.
To understand such a unique genius one needs to tune into frequencies of compatibility levels which have a combination of intellectual sharpness, emotional concern, social responsibility, humanitarian compassion, pride in the positives of one's culture and boldness to deride the negatives and above all a combo of romantic and aesthetic sensitivity which was encapsulated in clarity, conviction and courage.