He wanted parity with Arteta and Everton wouldnt pay him those kind of wages
He was then offered more money and a better chance of winning things at a more ambitious club so he took them up on it, so I dont really think you can blame him
The fact that it hasnt worked out for him is Evertons gain. He is desperate to come back and it seems our players are just as desperate for him to return and more importantly , as you pointed out, he makes us play better so I dont get why any Evertonian wouldnt be chuffed to have him back