I know these would e controversial but here it goes:

1. You want fabs in a country where IP laws are protected so third parties don't get their designs stolen.

2. Critical tech from a military/trade perspective.

3. Other governments don't get to introduce secret low-level artifacts such as microcode into chips which runs whole world.

4. General availability of a higher level of capital for research.

5. The confluence of talent from all over the world can contribute to state of the art advancement.

Nah, you should look at how China's supply chains are set up, you can get chips half a mile up the road that would be 30 miles away in the US.

It's not even labor cost anymore.