[Zanoan]

Well I don't mind Itachi suddenly becoming a good guy for that matter.

My guess so far would be that the Uchiha clan as a whole are to be considered as bad, since they summoned the Kyubi (Nine Tails) approximately 15 years ago. They lived on a lie where they wanted to be considered the good guys of Konoha. Any how, Itachi, as the hero he is, makes a pact with some higher ups in Konoha (Third, prolly, and some others) that he is to wipe out the clan. It can be totally random why it is him, but say that it is because he's a damn great shinobi would be fine to me.

Afterwards, if he was to kill himself, or atleast - he would continue the act as if he was the insane murderer and the Uchihas were still the good guys, seek out the Akatsuki fellas and perhaps work as a spy. Or, here he decided not to kill himself and join the Akatsuki, and who wouldn't want Itachi in their ranks?

Anywya, the deal for wiping out Uchiha was that one remaining member was to be spared so the clan/blood limit wasn't all lost - and the remaining fella should never be informed about WHY the Uchihas were wiped out in the first place/or what terrible powers they have, so whatever remnants or offspring wouldn't get the idea to try something like that again.