[beedogs]

You're the first one to hit on the real reason: these workers are stuck with Microsoft as an employer for years. If they quit, they have to leave the country.

This basically buys Microsoft six thousand wage slaves, in the very most literal sense of the term.

[gaius]

The H1B system is a textbook case study in regulatory capture http://en.wikipedia.org/wiki/Regulatory_capture

[mseebach]

Read my reply to lusr. Your use of the word "literal" isn't exactly warranted.