Why have the prices of Marantz and Sansui speakers have gone up so much? Whyyyy???

Why would you want these way bellow average speaker that sound like garbage.

I would never pay the current asking price on the Pioneer CS-63DX speakers currently offered online. I purchased a pair of them in 1970 (in the Navy on Okinawa, so highly discounted). Nor any of the other Pioneer or Sansui models of that vintage. Great pieces of furniture that played music however.

Having spend 3 years in Japan courtesy of my Uncle Sam . I feel confident
that, at least back in the day, Japanese voiced speakers for Japanese music .

That's very interesting schubert. I have long been aware that British speakers share a voicing, one prioritizing natural vocal and instrumental timbres. Traditional Japanese instruments and music have a very different sound than does Western music, so why wouldn't their speakers be voiced differently than Western speakers? 

Something to consider: my 55 year-old ears don’t hear frequencies above 16khz. As such, my recapped Marantz Imperial 6 speakers sound (to me) as good as, or better than, many modern speakers costing 10 times as much. Smooth, creamy, and eminently “listenable.” Younger folks with fully functioning ears are most likely hearing things which are completely lost on old farts like myself ;-). As far as the Kabuki speakers sold by the likes of Marantz and Sansui (among others) back in the day, they were always a joke, but some folks get a kick out of them. I get that. Fun is fun...