Too add something else I didnt see anyone mention is that Itachi's role in Akatsuki was more a deterrent against attacks on Konoha by Akatsuki. This is backed up by Madara when he speaks to Zetsu that Konoha is no longer off limits now Itachi is dead. As part of the deal Itachi made with Madara was to leave Konoha alone.
If Akatsuki had threatened to destroy Konoha they possibly could have forced Itachi's hand to respond in some way. To be blunt there is only one person in Akatsuki who could have stopped or killed Itachi and that is Pain.
What chakra type are you?
Here's something that's been bugging me: do you think, since the start of the Shippuuden series anyways, that Kishimoto has planned for some things to be explained by the anime, instead of directly putting them in the manga? For example, when Jiraiya finally recognized the various Pain bodies right before he died, he stated that they were faces from his journies, but nothing more was said in the manga. But, when the anime released episodes from that point, they expanded on it. Do you think he's given the people who make the anime some things to use to expand the story so it doesn't break the pace of the manga?
Since day one, Pervert never believed that the attack 16 years ago, was a natural dissaster.. pervert feared that a high-skilled shinobi was behind the attack and pervert knew that Minato wouldn't do anything without a plan. sealing only a part of Kyuubi inside of Naruto and not sealing the whole beast inside of himself, was all a favor for Naruto. So he probably began searching for intel about a secret organisation or something related. Every detail he heared, he told specific shinobi's in Konoha about it; like Kakashi. Also, what could akatsuki do against Konoha at that time? Madara made a deal with Itachi for not attacking Konoha.. like POW has stated:
and the one I bolded; Soo true.. I thought about everything, to convince myself, that Itachi could have beaten Pain, but after lots of information, I came to realize that Itachi couldn't beat Pain. All the rest in Akatsuki, he would wipe their asses.
... You're Dead 2 Me Now ...