Sure - but the visa madness predates the TSA/terror madness if I'm not mistaken?
Yes, but it was much easier before September 11. Uruguay was in the Visa Waiver program back then.
"Following the September 11 terrorist attacks, the George W. Bush Administration decided to tighten entry requirements into the United States"
That's only true for countries under the U.S. Visa Waiver, which are maybe 5% of the world's population (basically European Union and Australia).
For the remaining 93% of us, we have to think long and hard and plan far ahead before visiting the U.S., and that means being aware of all the issues or risk deportation.
http://en.wikipedia.org/wiki/Visa_Waiver_Program
And yes, I believe it does affect conversion significantly, but, coincidentally, we're the poorer 93% .