BS. It's all about the cheap labor. Several years ago while Michael Jordan was still playing for the Bulls, a story came out that Nike was playing Jordan and a few other famous athletes more than all its 30,000 factory workers in Asia.
In the past, I've read that sneakers made in Asia have a production cost of around $8 to $12, probably a little higher now.
Nike has healthy profits margins, and also spends incredible amounts on advertising and all the endorsement deals they make with athletes and teams.
As much as some want it to be something else, the primary reason companies move factories from the US to cheap labor nations is: cheap labor.
Run a shoe manufacturing business for 5 years, then get back to me.