I’ll give you two reasons some people are doing this:
IRS Form TD F 90-22.1.
http://www.irs.gov/pub/irs-pdf/f90221.pdf
IRS Form 8938
http://www.irs.gov/pub/irs-pdf/f8938.pdf
Good for them!
Their free choice.
Their freedom, as upheld by judges.
Their pursuit of liberty and happiness.
We’ll know it’s really bad when American citizens sneak into Mexico to pay lower taxes or get better quality, for profit healthcare.