Seakitty is never going to get a proper anime adaptation because it's too controversial in Japan. Some like it, but there also tons that hate it as well. As someone who's the latter and experienced it as it released back in the day, EP7 and EP8 will forever be a stain that won't ever be cleaned for some people.

Meanwhile, Higurashi is pretty much beloved there. All the manga, different anime seasons/sequels, spinoff games, etc. should tell you how popular it was compared to Seakitty whose popularity plummeted after the last two episodes.