my ipad in portrait mode has more vertical resolution than anything short of a 5k imac, but they didn't put it there either.
i'd still say all day is time-sensitive... all day! and they also managed to fit it into the 1/3rd screen-height events list in the calendar app itself.
anyway, you guys are correct, the debate at this point is academic whether it was intentional or a mistake. i just hope they address it, as i hate having to go to 3rd party solutions when the built in option is 95% of the way there.