I don't think Kirito was dissatisfied with his amount of money, but instead confused. This episode made clear he had a ton of money.
Hasn't it only been like a day or 2 since he met the guy at the hospital? I think he still has a decent amount of time left.
If Yui was just an AI pixie that was programmed to call its master "Papa", why would there be a "Mama"? That doesn't really follow at all. Leafa is obviously confused by Yui, but she doesn't seem to consider it is some super advanced AI. She's too busy focusing on Kirito himself.
He seemed to have some kind of reactive explosion type ability he used the first time he was getting owned.
But the real answer is probably just that it looked cool.
I was pretty impressed with the aerial battle this episode. Hopefully we get some more cool battles.