Did Devin Hester make a mistake by not wanting to return kicks anymore?

Yes and no. I think Hester became known for being a KR. He was good at what he did, but the problem with being a great KR is, the opposing team will likely kick the ball away from you making it harder for you to get any returns. Its obvious that he's one of the best KR's in the game, but when you have such a reputation, you won't be seeing many come your way, so in that sense its probably best that he be a WR which is what he was hired for in the first place. But I also say no because he was an integral part of the Bears special teams. Without him doing the KR's, then the field position becomes squarely on the struggling offense. Him getting them down the field so to speak helped the offense in addition to scoring points by getting in the endzone. The way I see it, its a two way street for him. He's a great KR, but at the same time he probably is better off focusing on his main goal which is to be a better WR.