You're right Suraj - practices around names vary across India (and the world).

In places like India - there is some fluidity in social practices, across borders and communities. The Self-Respect movement did not have a hard stop at the borders of Tamil Nadu or just those of Tamilian ethnicity.

As you have also implied - many of these communities also had different naming conventions throughout their history. Many Malayalees use surnames, caste names and house names. Many Tamilians also chose to indicate their village of origin through their names.

What makes the Tamil situation different is two fold:

1) The prevalence of patronyms. A much greater proportion of Tamilians use patronyms than Malayalees and Kannadigas

2) Caste based surnames were semi-banned (highly discouraged) by the governments themselves. This didn't happen in the same way in other states