Why not apply for JFRV while in America?

I was under the impression that I should apply for my JFRV when I get to Taiwan, entering on a multiple entry visitor visa.
I got married here in America, my Taiwanese wife moved back to Taiwan, now I am going to join her.
I talked to my local TECO in Seattle, and they are telling me to apply while still here in the States.
Should I do it?

EDIT: She said: " You can do either way, but you may want to consider to apply JFRV while you are in USA as it may cost more to apply in Taiwan.“

The cost of doing a medical check for a start in the USA is one reason. Do it here after you arrive.