Because apart from a few conflagrations Tamilians are slowly transitioning into the mainstream?
PDF is is cossetted in these terms. Tamilians learn Hindi, Ipose Hindi on them it is another matter altogether.
Tamilians put pressure in terms of Sri Lanka. But they gave up military aid LTTE elements long ago.
As a state, they have the third highest GDP, high social indicators, and is the most industrialised state in India.
They know now they have more leverage inside India.
This is more akin to the thinking of the Tamilians in Tamil Nadu btw.