Why don't KBO players move to Japanese baseball?

‌In the past, players who were considered top-tier in the KBO, such as Sun Dong-yeol, Lee Jong-beom, Lee Seung-yuop, Lee Hye-cheon, Lim Chang-yong, Kim Tae-kyun, Lee Bum-ho, Kim Tae-kyun, and Lee Dae-ho,
tended to go to the Japanese league more often than the Major Leagues.
But now, it seems like they are going straight to the Majors.
Could this be seen as a result of the growth in South Korea's per capita national income?
It seems like KBO players are receiving more money than Japanese players.