The "metrication" is a two-face issue.
Who commonly use metric system (roughly the 3/4 of the world) generally try to avoid tools and fixtures requiring a supplemental set of "exotic" screws, wrenches, etc., just like U.S. machinists generally don't have metric wrenches (¹).
Some time ago I looked for a spring plunger with a cylindrical nose. I found the perfect one in the States, but it was 1/4-20, requiring a 1/4-20 tap, an appropriate drill bit and a non-metric Allen key. Instead of buying all those things I gave up and used a different solution.
Very often it's even impossible to merge the two worlds: if I have a tooling plate with holes every 50mm hardly I can screw a Kurt vise on it, thus I don't buy a Kurt but I look for other "metric" brands. (²)
And I restrain from speaking of 110V/240V power tools and main plugs… (³)
This double standard means a severe limitation to the U.S. export which, seen in a wide domino-effect, has a great influence on workplaces, economy, etc.
I think a "metrication" of some products will give a nudge to the U.S. industry increasing the number of potential customers, even if it will make things a bit harder for home shop machinists.
Marco
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¹ A good reason to visit Europe: here metric wrenches and tools are a lot less expensive, and if you buy them during your holidays you can save on shipping… The best souvenir I brought back from the U.S. was a bag of 1/4-20 screws.
² At least Kurt has "hybrid" vises, with metric screws but holes spaced in inches. They are in the German literature.
³ Planning to travel abroad? Check
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets before!