in my case, an email alerting me to the change would have been completely acceptable. (Preferably a change which would not have meant rebooking me in a now online-unchangable itinerary.)

It's 15 minutes. Admittedly, the new flight is 15 minutes earlier, so the notification is more important (to me) than if it were 15 minutes later… but still… is anyone actually canceling over a 15 minute change?

Oddly, I've yet received no notification for my other, much sooner upcoming itinerary, which has a 15 minute later schedule change.

So very, very odd.