Their wit is what keeps the show going. Yes, there are smart characters, but that's what makes the show... the show. I mean, the whole reason Lorelai went to Emily and Richard was to get money for Rory to go to Chilton, which she had gotten into because she was smart. Without that, we probably wouldn't have seen much of the Gilmores, and they are a huge part of this show. And April was supposed to wow Luke. I think that her intelligence helped Luke's self esteem, knowing that he had *hem* produced *hem* a child like that. And because Rory went to Chilton, and then on to Yale, she encountered many smart people. So, the intelligence of the show is truly what keeps this show going.
If that makes sense.