What you fail to see is most people that use pc's have lower then a 390/970 atm.
Thats the market AMD hope to get with this mainstream card.
Its easy to forget on a forum like this with so many having a 390x/970 up that really thats only a small portion of the market
And what you and many others fail to acknowledge is this market AMD are aiming for could already purchase an 8GB GPU for ~£240, with R9 390 like performance for over a year now. It's called an R9 390.
8GB RX 480 at the expected £230+ price point needs to be between 390X and R9 Nano speeds to be a worthwhile price/perf upgrade.