Actually, ASA crews are instructed to announce flights as 'Delta Connection flight 4XXX operated by Atlantic Southeast Airlines.' However, given that ASA has been around since 1979, it's people, especially the more senior flight attendants and pilots, are accustomed to the 'older version' of identifying things, etc. Personally, I'd prefer that we all announce the same, dress the same, serve the same, etc, however, with DCI allowing each carrier to operate independently with a lot leeway, it's difficult to create uniformity throughout the system.
ASA management has repeatedly spoke of a 'seamless travel experience' for Delta's customers. However, with the same management unwilling to foot the cost of complete uniform replacement, failing to communicate with other DCI carriers and refusing to follow their own guidelines, I doubt that we'll see a major 'streamlining' of the customer experience.
DCI wants the job done at the cheapest price. Hello Chautauqua.
Ignorantia juris neminem excusat.