For what it's worth, there's no malevolent intent behind schedule change notifications (or the lack thereof). The fact of the matter is that the information sent out is 'scraped' from the e-ticket itself, and while the itinerary may have changed, the e-ticket must be reissued to match it before notification can occur.

Unfortunately this isn't an automated process and requires manual intervention on the part of agents, usually from the call centers, who are also servicing inbound customer calls (which is their number one job). Also, as has been mentioned in the past, some tickets purchased nearly a year out may experience multiple changes (some minor, some not-so-minor) and each one would potentially require the ticket to be reissued behind the scenes before the notification e-mails or phone calls go out.

Generally AS does a pretty good job of advising customers of schedule changes, but at this point immediate notification does not occur. I know it's being worked on so customers will have a greater advance notice window (along with the option to accept the change or find other options on the website) but have no ETA on that.