I agree! I would want something similar. I was thinking of something much simpler to start off.
Scenario: I must be in another town by 9:00AM in order to be ON TIME at a very important appointment. I set my starting location and my destination's location and Waze, the night before that would feature an alarm, based on the time it takes to get there, to alert me when it's time to go. Maybe I have to leave at 8:30 since there's light traffic reported. Maybe a major wreck, so I get my alarm at 8:10 based on the extra time it would take due to the heavier than normal traffic.
This would be very convenient for most everyone who has a doctor's appointment, an interview, or just anything that requires you to "budget in" extra time because of unseen circumstances, and it won't make you late because of traffic or any other road problems.
Worst case scenario, you leave extra early and arrive extra early
and believe me, I'd rather be early than late.