Two clarifications: 1. The visa quotas are perhaps reasonable based on the needs of legitimate businesses, but the mad rush/lottery I mentioned is probably due to the glut of "fake" companies that exploit the system, that this story is about. Or perhaps these are a product of the system itself, which leaves no safety net for legal status in the event of loss of job, or inability to get one right out of college or grad school. One really has to get another job in a month or two, or risk being "out of status" if one stays and the USCIS gets to know that one's visa is cancelled due to job loss. Being "out of status" (essentially temporarily illegal) could prove detrimental to subsequent green card/citizen applications, or international travel . Perhaps these companies are serving that niche, other than those from the outside that want to come here and work. There is also the "spouse punishment" i.e. H4 visa which does not allow spouses of H1 visa holders to work unless they get their own visa. While this sounds reasonable on paper, as a real consequence there are a lot of H4 spouses that sit at home (or work illegally!) when they could be productive, and lately people having difficulty getting married (to someone back home) and having their spouse join them since they know of this situation. 2. Microsoft does have a facility in Richmond, BC or some other place "just north of the border" for precisely this reason.

Thanks @Xeleema for requesting comments from an Indian immigrant to the US. I believe if you read carefully there are different versions of this perspective near the top of the comments thread, but here goes, anyway:

Different reasons depending on the route one takes. For those like me that took the educational route, perhaps it was disillusionment with things back home coupled with having a dream and a getting new opportunity to start things fresh and try something that wasn't possible back home. As India has developed, and as there is awareness of the "cons" of US life too, those like me are in the minority.

As an evil fox character in my daughter's favorite TV show would say, "Oh man!". I'd sum up the challenges for legal immigration as a potent mix of unreasonable visa quotas and dealing with a slow, needlessly complex system (that almost makes illegal immigration look good by comparison). As an example of the former, in some cases people have graduated from US schools with a job offer which they couldn't accept because the visas ran out on the very first day and the resulting "lottery" didn't favor their application. Why would today's youth choose to suffer this when other developed countries (eg. Canada) will give you a green card out of college even without a job offer...
As an example of the grinding wheels of the system, I'm a PhD scientist doing very specialized (not run of the mill IT) work, and my application took 6 years to clear, including many frustrating delays and redundant requests for fingerprints or documentary evidence already received by them. It seems USCIS is accountable to no one in this matter (especially not their legal immigrant customers who keep shelling out hundreds of dollars for employment and travel privileges while waiting for cards to arrive year after year). Again, why would... as above.

With a green card and a career, I suppose... but I'll contort the question to answer a related one: why don't I go back, now that things are better. I believe we might some day, but for now what we gain by being here still outweighs (somewhat) the high cost structure for homeowners/parents, losing out on being near parents, and other reasons for being in India. For many many of my friends who've been trained here but have different constraints/expectations than ours, the answer has been clear cut, and they have indeed returned to India.