If game ends up:
- fun to play (immersive, addictive, not grindy, not dull)
- smooth performance wise (both lag free and offering good FPS on mid range machines)
- balanced PvP and PvE wise, with lots of activities of both type to perform
- filled up with nice community of players
...then I personally don't care if graphical assets are from asset store or custom made. If they are custom made it's a bonus. If they aren't, and above 4 points are filled, I don't care.