If yesterday showed us anything, it showed that we needed more inspiration. I'm not writing this article because he scored twice, he didn't show up for 70 minutes and that's a problem. I think that, in the absence of Fabregas and Vermaelen, he should get the armband. He has never really performed at Arsenal and his problem is confidence.
If you watch him from his Marseilles days you see a completely different player in attitude. At Marseilles he was the biggest player, along with Ribery. At Arsenal you see a man who is behind Fabregas, Van Persie, Rosicky (when he joined), Arshavin, and Vermaelen.
This creates the problem where he is expected to grow, rather than where he is expected to perform. The biggest mental block is Fabregas. Fabregas is the same age as Nasri, and a much better player, currently. Nasri is meant to be Fabregas' replacement, though he's not as good as Cesc.
At many times in his career, he was called the next Zidane. Since then he has fallen down the rankings. We know he's got excellent vision, trickery, determination and even shot power. If he was captain he would become a larger part of the midfield. He would be able to control it rather than be a player in it.
Basically, it would allow him to recapture that Marseilles mentality where he was THE big player and didn't everyone know it. If we are grooming him to be as important, but crucially not the same, as Cesc, then giving him the armband this season would be a very good idea. I believe it would accelerate his development and give him room to grow.
Right now, he only has to be better than an, unfortunately, declining Rosicky. With the armband, the other players would look to him for inspiration and I believe he would provide.
I'm not saying he should be captain above Cesc, only that he should be above Rosicky and Almunia.