here's an Indian (entrepreneural) perspective.
Let me start with a few stories:
The founder of Snapdeal http://www.snapdeal.com/ (an India focused ecommerce company) wanted to do a startup in the Valley but didn't get a visa. So he decided to stay back and do his startup in Bangalore. Snapdeal is now valued at ~$10B and is challenging both Amazon & Flipkart here. Their YoY growth is 6x.
Zomato http://www.zomato.com/ started of by consolidating its presence in India and has now gone multi-national (15 countries and expanding). They haven't gone to the US yet.
There are quite a few startups happening here that are focused on India, the rest of AsiaPac & EU regions and a lot of these have just begun to scale. These startups have started taking the cream of the Engg folks who would have otherwise gone to Infosys, Wipro and from there on to the US.
In fact, I know of a couple of headhunters who place US engineers with Indian startups in India. It is a trickle now and I think it would be good to cherry pick the better ones from out there. There are lots of seriously good engineers who we can use.
As an entrepreneur/co-founder myself (of an early stage in the enterprise space), it makes a lot of sense for us to be India and AsiaPac focused - We have a large market that we would convert first. First of all it is so much easier for us to sell in my backyard and then I honestly don't have the time to wade through all the Visa & other issues that the US would throw at us.
The only reason I would consider the US is the size of the market which will be important to me once I've consolidated and have become profitable. The market that is right in front of me (India and then China) is large enough for me to grow to be a fairly large entity.