From the days of the Travancore sisters Lalitha, Padmini and Ragini, Malayalam actresses have been making it big in other South Indian languages, especially in Tamil. In the 80's, there were Ambika and Radha. Look at today's list: Nayantara, Asin, Gopika, Meera Jasmine, Bhavana, Meera Nandan, Navya Nair, Renuka Menon and Shamna Kasim (Poorna).
Why do Malayalee actresses migrate to Tamil? Is it because Malayalam cinema has become superstar-centric and the genre of heroine-oriented films is fading out? Primarily, the advantage of Tamil cinema is the glitz and glamour plus the huge pay cheques compared to Malayalam. Today a top heroine in Tamil makes between Rs. 50 lakh and 1.5 crore per film.
Nayantara has refused many films since the producers were not able to meet her demands. According to some reports, Navya Nair is getting paid ten times the salary that she got in Malayalam. After doing one film in Malayalam, Meera Nandan is now doing two films in Tamil -- Valmiki and an untitled film. She is now more comfortable in Tamil where she is in the 5 to 7 lakhs bracket.
Secondly, the chances of getting lucrative endorsement deals and stage shows abroad are much higher for Tamil actors. Many Tamil directors prefer Malayalam actresses, since they can emote much better than North Indian girls who do not understand the language, nor do they grasp the culture.
When the pay is high, some compromises have to be made on certain issues. But the actresses also know that their staying power is limited. Their logic seems to be to make hay while the sun shines.