Wow... this analysis is really well written. i really liked how you described Axel's 'obsession' with Roxas. personally, i'm an Axel fan, but i've always had a hard time explaining to others about Axel, and this analysis describes it really well.
also, just my own thoughts... but maybe the nobodies aren't exactly devoid of feeling. as in the previous posts, KH is based a lot on metaphors of the heart, so if we use that as the concept, the 'emptiness' is not just a lack of a heart. in human terms, a heartless person is a cruel and merciless person. this, however, is based purely on personal morals. the organization aren't exactly cruel, they are fighting desperately for their goal. in kh, 'heartless', and 'nobody' are different entities. nobodies are empty. in human terms, an empty heart is a heart that has been hurt, betrayed, and therefore devoid of hope, and dead. perhaps this is the same for the organization. they had probably been hurt, betrayed, so become afraid of emotions. everyone in the organization are maybe just afraid to be hurt, so they avoid feeling anything at all, just as humans do. in this aspect, perhaps they are not unable to feel, simply they are elites that have been hurt especially badly, so are more fearful of pain.
Axel had begun to change after COM, as Roxas said in days when they were having ice cream. if he were really such a bastard throughout COM, then he wouldn't have been any different when he came back. but he had changed, without Roxas. so that means he is capable of feeling, after seeing what happened to Riku, Sora, and namine. even though he looked as if her were thoroughly enjoying eliminating his companions, at the end, he looked as if he were tired of all the plotting of the organization. he was already starting to develop in COM, but just slightly, so a lot of people were still pissed about him killing their favourite character.
one other thing, my friend was pissed, saying that Axel betrayed Xion in days. and i was quite interested in that. it is true that he betrayed his important friendship for his wellbeing, but if i think that Axel knew Saix before the organization, and he did everything in his power to help Saix go up in ranks to achieve who-knows-what goal, he never actually betrayed anyone. he promised Saix before the organization something, and he never broke that promise, even if it meant destroying what was important to him. Axel never promised Xion anything, or Roxas, so what was wrong with trying to satisfy both sides? he tried to stay true to his friends, but at the same time to not betray the organization. it got him killed too. he was always by himself in that aspect, without anyone to help him. so he wouldn't be a bastard, since he never did anything that went against himself.
i'm sorry for my rant. but seeing this really got me thinking.