To reproduce, create an event called "beach party" on some friday.

The event receives a timestamp equal to the current time you made the event and a duration of 1 hour.

I dont think making assumptions about time is a a good idea, a few reasons:

 * It seems unlikely to me that an event you create on some date happens to start the exact same time of day in which you create the event.
 * My beach parties are rarely just 1 hour.


The consequence of the current fallback is that I always have to press "Edit Details" to change the time.

I think a more sane fallback is to have no assumption about specific time. All you know from user interaction is that it is going to happen on that day (unless the user dragged over several days). So I would suggest to use "All day" by default[1]. Some users like me rarely cares about specific time for events and users who really care about having specific times on events would most likely have to edit the timestamp anyway.


[1] This is also what google calendar does.