In 2004/05 Rijkaard played Iniesta at CM and on two wing positions, not because that was a genious move by Rijkaard but because of injuries.
We started that season with a smaller squad and in September lost Edmilson, Motta and Gabri with broken knee ligaments.
Larsson was injured iirc in November, also broken knee.
So, our attack was left with only Ronnie, Etoo, Guily.
And midfield with Gerard, Xavi, Deco and 20 years old Iniesta.
Marquez was moved to a CDM to add some physque and muscles and Iniesta was the only player left who could have played as a winger here and there to give some rest to 3 attackers.
In 2005/06 with a return of Larsson and the addition of young Messi and another sub Ezquerro, we had 6 attackers so Iniesta lost his winger position.
And since Xavi broke knee ligaments in December of 2005, our midfield was stacked with too many workhorses in Motta, Edmilson, Van Bommel plus Marquez if needed. And without Xavi, the only true creator left was Deco.
This is why Iniesta started to play as a CM in that season, especially when Deco was injured, rested or suspended.
My point: playing Iniesta as a winger wasn't a genius decision but the only solution left in a short squad heavily decimated by injuries.