When I add an event to my Google Calendar, I usually want a reminder of it. If it's for my personal calendar, then I always want a reminder. If it's for another calendar, I probably want a reminder. If it's for calendar XYZ, maybe I never want a reminder.
Since I don't trust SMS reminders, and seem to trust email reminders, I probably always want an email reminder. Or whatever the push reminder protocol of the day is, but it has to trump any other notification.
That's not the main point. I also want the setting of when the reminder to happen to be contextual. An example:
if I have an with the next 2 or 3 days, and it's in the morning (say, before noon), I always want a reminder automatically set to trigger about an hour before I go to sleep the night before
if the event is in the next 2 or 3 days, and happens in the afternoon or evening, I want automatically set for 2-3 hours before. That gives me enough time to travel to that place, usually in the same city
if the event is at least a week away, I want a reminder automatically set for 2 days before, because I may have forgotten about it
if the event is at least a month away, I want a reminder automatically set for a week or so before the event