It is not enough just to produce talent, it is also necessary to have structure in place to utilize/absorb the talent. India was far from that position before, it is somewhat better but still far from ideal.
To turn the point on its head, if you have the infrastructure and environment for talent to be used and valued, they would come, and they did, to USA. However given the strong anti immigrant rhetoric that is becoming popular in USA I am interested to see how this is going to play out.
China also didn't have the infrastructure. In fact India has a lot more infrastructure than china did due to 200 years of British Rule. The difference is China forced their brightest citizen to stay and build whatever infrastructure was needed and also didn't so easily give in to pressure to open up to trade that didn't benefit them in the guise of "globalization".
Not everyone in China is Han Chinese but it is not as diverse as India. Should the Indian Gov't suppress all the different religions in India? Crush ethnic tensions with brute force?
To turn the point on its head, if you have the infrastructure and environment for talent to be used and valued, they would come, and they did, to USA. However given the strong anti immigrant rhetoric that is becoming popular in USA I am interested to see how this is going to play out.