Kasthuri is an active commentator regarding social issues through an occasional column with the Times of India and via Twitter, and her tweets have sometimes elicited debate in the media. In early 2017, she questioned Rajinikanth's ability as a potential politician, and her opinion garnered criticism from the actor's fans. In late 2018, she criticised Rajinikanth's ignorance over the Rajiv Gandhi assassination case and engaged in a further exchange with Rajinikanth's supporters. Kasthuri spoke out as a part of the Me Too movement in India, suggesting that her reluctance to give into patriarchal behaviour meant that she was removed from several film projects. She revealed that one male actor took a particular vengeance against her for her rebuff to his advances, and subsequently made it difficult for her to work on other projects. She criticised directors Bharathiraja and S. Shankar on April 2019, she said director Bharathiraja and his son has black skin and they use North Indian girls with lighter skin in their movies while S. Shankar goes a long way and imports white skin foreign girls in his movies.