In Kakashi's mindset thou he could view himself as responsible for obito "dying". If he had been better, stronger, perhaps Obito wouldn't have had to "die" protecting him. I still doubt that Kakashi got the better eyes. But hasn't his sharingan improved once since he got it from a two to a three? I forget what it was when Obito had it.

The thing is it seems to be a mindset of the sharingan user. How does an eye really know if you've killed your best friend? There ends my out of the box views.