The DateTime column type is fantastic for calendar view, and calendar view is great for exporting to other calendars. One main feature in most calendars on, for example, the iCal format, is the ability to create events that don’t have a specific time. These are usually marked as “all day” events. Or they could be useful for things when you know what the date is, but you haven’t figured out the time yet. At the moment, the workaround appears to be let the field default to the time of midnight. It’s workable, but I’d love to see the datatype be able to handle something like “null” for time.