Agile, and Scrum, basically pick an end-date and the development teams pick features they think they can get out the door by the end date - during the process there is continual evaluation of progress and if they think they're going to miss the end-date, they drop features until they meet the end date. Hopefully, the dev teams get better at estimating how long what they're doing will take, and the estimates get more reliable.
From CCPs point of view, I suspect they'd rather get out
something than push it back, since this is essentially a giant beta-test of their walking in stations stuff. The sooner it gets into testing, the sooner they can get to work on fixing the bugs. There will be bugs, and they will be found and some of them even fixed.
The art resources for producing the other brands of captains quarters seems to me to be less critical as far as the finished product goes, because if the quarters look great, but you can't dock with the sofa without getting hung up on the coffee table, then it will fail.
It's not like any players are desperately looking forward to the changes in this expansion so much that they'd pitch a fit about it not being released on the 21st.
I'm fairly relaxed about the whole process. and if you don't care, do what I do and check the box saying "don't load the station interior" until they have one you want to look at.