Some families for years used the "necessary family business" loophole to continue communicating with their disfellowshipped family members. Not all, but some. I know of several families who did this.
As far as the people that greeted you at the hall, they may have forgotten or not realized you were disfellowshipped. In my experience, some elders always greeted the disfellowshipped ones if they had an opportunity. Not all, but I saw some do this multiple times. The reasoning my elder dad gave me was that, "Elders still have to communicate with them to see if they're ready to come back."
Regarding dress and grooming, in my lifetime this has always been dependent on the local culture.
In South Texas, coats were never worn in the door to door work during the warmer months. The brother conducting the meeting for field service was instructed to wear a blazer during the meeting for field service. But that's about it. From time to time, we'd have a circuit overseer come through the area that came from a different region of the country and his first visit he usually admonished the elders and ministerial servants about wearing coats in service. That usually only lasted one visit and by the next the CO would realize why it wasn't a thing in South Texas (weather.)
I had family that served in Mexico (need greaters) and heard tales about being able to go in service and bookstudy without ties.
This recent announcement just makes it official organization-wide.