Dravidian beliefs are more prelavent in TN and so God Ram does not win any votes or sympathy from most of the people.
TN brahmins made ram as some sort of sophisticated GOD and so all the other castes either worship the local gods or being attracted by dravidian politics. And that is the reason on why the leaders can survive in TN after pouring dirt on hindu gods. It is basically because of caste equation and also because the gods that are being worshipped by other castes are mocked at. or not being given any relevance.
And Mr singh needs the support of Dravidian politicians to survive in power and hence the indifference to a perceived monument !