You can use date as a trigger (with a time, since a date is rather a long period of time). Check out Periodic Schedule as the trigger.
It's not contrived at all. It's the logic of an automation system. It's how they work. There are discrete events (e.g. a button being pushed), and there are conditions that are not events at all (the door being left open). You cannot build automations with only one or the other.
The original Rule Machine had Rules with Conditions. In effect, IF (door is open) THEN do something ELSE do something else. However, for that to work there had to be two events to trigger it -- two implied events: the door opens and the door closes. The rule would be true if what triggered it was the door opening, and it would be false if what triggered it was the door closing.
Now, you can certainly create that same rule now, with both triggers. We added changed to simplify the rule. In either case you would still need to test if the door is open or not, just as in the old approach. What we did in Rule 4.0 was to make these things explicit, instead of implicit. The reason for that change was that people were always confused by things that were implicit, that could not be seen.
What we know now is that everyone thinks in a different way. Some people are very comfortable with one approach and can't figure out the other. What to do? I suppose we could have both approaches at the same time, but then that would totally confuse people. So we settled on making things explicit. In the old approach, the implicit things worked exactly the same way the explicit things do now. The underlying logic is identical. One is hidden, and one is in the open. I figure it's better to have things in the open. But, alas, not everyone thinks that way...