I have been without a watch for a while and usually pull out my cell phone to tell the time. But, that is awkward while riding. It would be nice to have the time on my display as I am trying to get to a bus stop before the bus leaves. Others may want it for the same reason on their way to work. After battery level, assist level, and perhaps speed, time would be my most useful item.
When I turn my ebike off I would like to know there is no power drain continuing unless I have an alarm that I want connected to the main battery. I know clocks are very low power draw but maybe enough to add extra wear on the battery over time. I know it's not much but off should be off to me which would mean I'd have to set the time each time I power on the ebike.
I road a lot of motorcycles over time and never had a clock on one.