Features that I don’t personally believe in are unlikely to see the light of day, such as an unread-count icon badge. I believe unread-count badges signify unseen items with some degree of urgency or time significance that were triggered by other people or external events. Instapaper articles are added by you, aren’t urgent, and in most cases, have been seen already (when you chose to read them and clicked Read Later).

Marco Arment, Side effects of developing for yourself

Totally agree with the general philosophy, and with this point in particular. An unread count is something we’ve resisted adding to Twitbit against a sea of requests, for the same reason.