Yes, that was a shame, KMR.
We know that Vicki told Barnabas that David idolized him and that she could hardly get David to talk about anything other than Barnabas - but we never saw any of that. But then, Seth Grahame-Smith did tell us that practically the entire Barnabas/David subplot ended up on the cutting room floor. And apparently at some point it was decided that Vicki would barely be seen talking to anyone other than Barnabas because she also had scenes with Carolyn and Julia cut. (Though we also know that she even had at least one scene with Barnabas cut.)
I still say that if we can believe Seth Grahame-Smith that so many scenes ended up on the cutting room that they could have probably put together an entire other film from them, then apparently the script was just too ambitious for its own good. Well, at least for a film that would ultimately end up with a running time of under two hours...