I would like to add my vote as well. User selectable digest mails was a “Must Have” feature for us when we were evaluating new forum software.
Our forum started out as a mailing list in the early '90s, and until our last update many of our users chose the daily digest as their preferred way of following the action. Some of them have been doing that since the days of dial-up and Alta-Vista.
If anything, removing the digests will increase our mail traffic, and we will probably end up increasing the current 100 mails/day throttle.
Please restore the digest mode functionality. Make it configurable so that sites can disable it if they wish, but please restore the functionality.