The same reason you go for an American Strat vs. Mexican, I suppose

There are two Mexican Jaguars/Jazzmasters in present production that aren't humbucker/hardtails; the Classic Players are around $800 new and (in particular w/ the Jazzmaster) have a spec that causes me to rush and change half the parts out (actually I own one of these... Or the remains of one, that I tailored more to my preference.)
Then there's the 60's Lacquer Classic for $1k; actually very nice guitars, much better than MIJ spec. on every level, and MIJs tend to go for about the same price at the moment (when you're able to locate a new one.) On principal, I'm hesitant to pay that much for a Fender not made in the US.
Then again I'm really not in the mood to drop >$2k on an American Vintage, so if a somewhat stripped down model (but not immutably incorrect, such as the Classic Player almost is,) can be had for American Special/Standard money (~$1k - $1.2k,) I'll be interested. My recent Strat search and experiences with my own MiM guitars make me an American Fender believer, as much as the Mexican models are nice guitars.
(Back to the Mustangs and Duos, most Mustangs in recent years are MiJ, but there are now Mexican versions of both guitars; $500 , closer to what I want to pay for something MiM.)