I suggest getting them because of the impending doom coming ahead, which is known as the ... NINJA PAGE

This may be months away but .. it is a page that replaces fragments in shops..
You will need to have the Ninja's released first in order to get access to the newer ones, and special variations.

Like you have to get hidan before you can get infinite Hidan..
Kazuzu before his other form.

It also locks you out of be able to get other ninja's through shop means.
untill you get the old ones.
They may not implement this.. but I believe they will.