Earlier quoted context omitted.
Let me flip your question too: why do you think it matters?
Because all else being equal, that skew shouldn't exist. There is nothing inherent to Indian people (or any other people) making them better at these jobs, so there is value to understanding why their numbers are so high. And by value, I mean value to US citizens. It could show us how we can improve within the country, or it could expose fraud in the system. Or a mix of both.
Their numbers are so high simply because they represent almost a fifth of humanity - there are almost as many Indians as there are people in Europe, South & Central America put together.