People don't criticise him for his stance, it's his technique which is flawed and cannot do well outside Asia.
The reason for this is that just before the ball is delivered, he closes his stance, which all batsmen with this stance do, but he over compensates and brings his front foot ahead of his back foot, closing off his stance. Since this is done quickly at the last second, his balance at the crease isn't good, so he will struggle to hit on the leg side, and wont be able to generate power throught the off side. He also won't be able to play the short ball.
This issue has always been there and Fawad hasn't been bothered fixing it, he only has himself to blaim here. This is a major flaw that would get easily worked out at international cricket, and he was found out by Australia and he struggled against them.
Unfortunately the domestic cricket in Pakistan don't identify these issues, neither do teams do research about their opposition. These players get found out at the international stage.