My guess is that it got caught in the anime crash back then and it wasn't just this series that got broken since the dub of the Higurashi series also got caught up with it and as such only the first season of Higurashi is dubbed, it was most likely going to be more into the other seasons but it most likely got caught up in the so-called "crash", a sad time indeed since a good deal of very amazing (unlike the overflowing pieces of garbage nowadays... >_> ) anime series got caught in the "crash" and as a result many are incomplete, oh well...