Well, your proposed system can 't handle half hours efficiently. And the developer uses that. I've just looked up the weekday schedule and it has 23 events. It could possibly be -- at the cost of strange hours -- converted to hour schedules but that is stretching it. It has no room for more events and I can see that could be needed. Probably the developer saw that need as well and decided on the current system.
As said it is one click for opening the hour glass. Then -- yes at a different position, but not that far -- correcting the time -- mostly one click for both half or whole hour -- and then OK. It is not that bad considering the flexibility it gives. Anyway I stop here. I think you suggest a system which won't work in this game. Or constrict it too much for the little gain you get...