I've been in touch with a friend who has a 2K monitor and he is experiencing the same thing as me, also seeing a drastic improvement when running with DSR to simulate a 4K solution. So it seems to me that this is expected behaviour unless the devs want to take a deeper look into the AA settings on "lower" resolutions.

So the topic boils down to this; is this something you're aware of and can we hope to see any improvements to this in the future?