Eh, I think too much character development would be a bad thing, especially for a show like this. It'll probably drag out the encounters with other diary holders into several-episode showdowns. Maybe not if it was done right, like maybe if they had less diary holders, but that just might mess things up if it was trying to tie in as much as they can with the manga. Or perhaps maybe if they build up the characters correctly and were more than cool and unusual deaths, or something along those lines. I think they are doing a great job with the anime so far and I'm thinking about checking out the manga too, actually.