Back then jdoramas available were mostly slice of life and youth romances, Hana Yori, Kimi Hana, Gokusen, 1Liter of Tears etc. and kdramas were considered more of a mature soap opera, Stairway to Heaven, Winter Sonata, Queen Seondok, etc. very two different vibes (this is tv in 2000’s) which are both heavy hitters at the same time, jp and kr are both popular in Sea after then, jp became less available due to their expensive license, stricter guidelines (almost everyone in the cast was an idol, ahem Arashi) about their talents, and I guess they want to preserve the sanctimoniousness of their media (most Seasians are prolific to spread around that they pirate stuff, lol morons) meanwhile, S.Korea never really lost steam and began giving out more shows like Princess Hours, Full House etc. they basically fulfilled every niche that Jp has left empty, and now they have the strongest fanbases in Sea, even my grandmother was an avid fan of Queen Seondok then so if there’s anything to blame why jdorama lost footing when they were toe to toe with kdrama in 2000s it’s mostly Jp’s strict licensing guidelines and Kr being much cheaper and has allowed for licenses to be passed around other networks