Edit: Can somebody tell me what was downvote-worthy about this comment? This is getting ridiculous.
You're probably getting downvoted because your first question is a matter of public record and your assumption that he wants to be extremely visible is inconsistent with the number of interviews of a biographical nature he has conducted. Almost all of his interviews with the press have focused on the NSA, GCHQ, and the like. He explicitly redirects journalists to the real news when they probe too much into his personal life. In this light, your comment could be interpreted as a poor attempt at character assassination.
He wants to be visible as much as possible for two reasons.
The first is that this is the way for him to make the release of documents as effective as possible, something which he has been very succesful at.
The second is that being in the public eye makes it more difficult for organisations to lock him up or assassinate him quietly. The same reason why you'd arrange to meet up with a stranger at a busy public location.
Your first reason doesn't make sense because all the other leaks by secret leakers have caused uproar and changes, so a person behind them isn't necessary, clearly.
Your second reason doesn't make sense because as long as nobody finds out who you are, they can't kill you. Other leaks in the past have been done with anonymity. And honestly, they'll rendition him regardless of the public outcry because he's broken the law.
But yeah, he also comes off like a grandiose megalomaniac.