Iniesta does it and he is CM. He'd also be much weaker player, if he was playing on right side like Turan does. If Iniesta style is much better fit for left side of the pitch, why should it be different in Arda's case?
Iniesta does it way way way more rarely than he used to. It's no coincidence that Iniesta's best game this season was the one on Bernabeu, where Messi was missing. Iniesta's defensive work has been developed under Lucho, but as far as his creativity is involved, he has less chances of showing that in dangerous spaces when MSN are playing.
This new look of our midfield is the reason some fans who don't really follow Barca think we have a worse midfield than Bayern, Real Madrid or even PSG. When, in fact, our midfield is still the best, only different in it's role and functionality than the one we had in 09-12.