I buy packs every expansion so it's not that big a concern to me but I would be upset if I was F2P and crafted golden versions of these cards (reason doesn't matter) and then Blizz altered them without any warning. Essentially, the product you paid for (I mean that loosely) and were promised turned out to be something else and this happened with no notification beforehand. If I bought a $4 red shirt from Walmart and one day it transformed into a blue shirt, I'd still want my money back. It's about the principle and Blizz's failure to communicate with the fans is what gets me.
No. It doesn't change game-play whatsoever you shouldn't feel entitled to get freebies. And if you are that triggered by the artwork changes then just leave the game if you feel that upset by it, it's really unhealthy to feel that way over a video game.