I have Blackflag on PS4. I didn't even spot the difference between pre- and post update image. Nobody knew it was running at a lower resolution until the pixel counters and the guys with the pixel counting equipment came and called it out.
You are right, resolution doesn't matter an is a waste of resources. The entire gaming industry is full of idiots because they are wasting their time rendering at 1080p when they can render everything in 720p and noone could tell the difference.