Probably because of the crackdown on other companies with a lot of H-1B applicants like Cognizant, Infosys and Tata. There are a fixed number of H-1B visas available every year, so if it gets harder for some companies, it gets easier for everyone else.
That was literally the first thing that came to mind (I was going to make the same comment).
The change isn't that there has been an increase in demand, just that clearly nonsense "skilled workers" in the contracting companies have been blocked. Seriously, I don't see how a contracting firm could ever justify the kinds of "specialized experience", etc requirements of a - by definition - generic software developer.