When I got my car there was no AP/EAP difference. The car came with no AP, and you could only buy what they called EAP to which they added features like "smart" summon, Nav-on-AP etc. One of the features they added was turn-signal triggered lane change in AP.
So is that what you refer to or was there a time that people who bought a car which included "basic AP" and with that basic AP they got turn signal lane change? And later they took it away from basic AP, but not the grandfathered cars?
To my personal tastes, turn-signal lane change is pretty much all I use from "EAP." I use smart park once a month maybe. Can't see spending $6K for just that, but some people do. I would be pissed at losing smart park and park alert if I had paid $6K for them. As we all know, smart summon isn't smart, and regular summon is not useful except for a few people who have garages they can't get out of the car in.
Nav on autopilot I find discomforting, but others like it so perhaps that's what they are paying $6K for?