Over the years I have formed the impression that although most Indians are relatively dark skinned, most Bollywood stars are relatively lighter. I don't think this reflects talent or even that us white Westerners would find lighter skin more acceptable. If true it must reflect something deep in India, perhaps going back to when caste was more dominant. Conquerors such as Persians, Mughals and British were all lighter skinned and so maybe some people associate lighter skin with power. Not to be self-righteous colour is very much noticed in North America and in general the lighter the skin the more acceptable.
Kajol is one of my favorites. Married to Ajay Devgn who is also one of the darker stars. Her personality comes through as very likable. I remember one movie, "Kabhi Kushi Kabhie Gham" where Shah Rukh Khan's father played by Amitabh Bachchan seems to disapprove of her for reasons I would identify as class, but I also think her darkness identified her with the lower class. But she was such a bubbly person the hero was nonethless attracted to her enough to defy his father. The two are one of the most popular jodies in Bollywood.
Women stars are almost all relatively white. Katrina Kaif, Kareena Kapoor, Preity Zinta, Priyanka Chopra and many more.
Beauty and self worth are very personal. What do men and women feel attracted to? What traits are less attractive? Radiant skin is sought after by all and could be a reflection of health. As a relatively short person I am aware that in general taller men do better in business, politics and socially.
I enjoy a wide range of Indian actors, but as an outsider wonder if I am seeing the real India. For that matter is realism what we crave from Hollywood or Bollywood? In reality Hollywood usually projects a glamorous world which is what we prefer most of the time, but I like to see realism once in a while.