The main reason why these foreign companies are opting India is due to the simple fact that India has many graduates and unemployed youth who are ready to accept a job with less pay then their foreign counter parts. Due to which they will gain more profits.
India has large number of graduates and postgraduates in each and every field such as science and technology, IT sector, arts, etc.
As the graduates and postgraduates in India are ready to expose themselves to the world of competition, they are ready to work for less pay. The main reason for that is, the people want experience and exposure to different environment where the chance of learning several things is more.
Money matters less for people who have the capacity to prove themselves. The foreign companies in the present that's openings their branches in India because they knew that Indians are hardworking and they have the zeal to accept and work for the upliftment of their country
If we consider the opportunities for Indians I think there are more opportunities in India than in US or any other country abroad as most of the mnc's are opening their branches here.
