Well, if I were only running one league/one draft, I wouldn't mind going to two picks per day. However, with the chance that we could end up doing multiple drafts at the same time, I figured maybe one pick a day per draft would be enough for most folks to keep up with.
Also, given the fact that even if we started drafting tomorrow, it's going to be at least five weeks or so before the 2014 players are released so that draft would be in no real hurry.