One thing about Akatsuki is that they don't really care who dies or who lives. The reason they had Kukazu was because he was very strong. That and he was good for collecting money, part of their goals required money.
I was under the impression that Hidan was recruited not mainly because of his strength, which wasn't much in comparison with the other members, but because of his immortality. He was the only one who could be Kukazu's teammate when Kukazu went berserk.
I think those two are the exception. The other members are very powerful. One unique thing about Akatsuki is that each of their members is expendable. They aren't friends, they don't try to get along, because they know that they aren't completely nessissary to AL's plans.