It is mainly because of the name and the fact that the Minimoog was the first of it's kind . The first that required no patching . As for why people buy Polymoogs , you're guess is as good as mine . People by the Memorymoog because it's the only real polyphonic synthesizer that Moog Music made . Remember , by 1975 Bob Moog was out of the company . The Realistic MG-1 is actually a good buy because it's basically a Moog Rogue but with some differences .

The Rogue's oscillators are not independantly controllable , the MG-1's are . Plus the MG-1 has a square wave polyphonic oscillator , the Rogue does not .

But , yes , to answer you're question the Japanese synthesizers are cheaper and have more features . By 1983 the Japanese companies squashed all of the american companies . Sequential Circuits managed to spit and sputter till the late 80s .

Being the first does not mean you are the best , it just means you are the first . Plus prices are coming down . I still look on Ebay becuase that is where people tend to be the most idiotic as far as what they pay . I'm seeing alot of Moog synthesizers with high reserves and no one is bidding on them . Same with the japanese stuff too .