7970 was a 350mm^2 core, the 680 was 300mm^2, Fury X was 600mm^2, had an AIO and more expensive memory yet cost about the same as a 980ti without the AIO or more expensive memory but was also about 600mm^2.
AMD price based on a sensible/fair margin and the actual production costs. nvidia just look out and decide how much they can get away with ripping off their customers and when AMD don't let them(680gtx) they price with a fair margin to their production costs.
Nvidia is charging you 600mm^2 core pricing for 300mm^2 cores. AMD won't suddenly charge £600 for a ~350mm^2 core.
I don't think Joe Public care for what size the die is in truth and buy on performance figures. This is where AMD really need to nail it from the off. Release a card that consistantly beats the opposition and you have a winner. No good a year down the line and has to be from the off.