This was WAY before Shippuden was even concept in depth. Hell, I doubt "Pein" was even close to being finished at that point. It was something at that time was incomplete and is now finalized differently. Stuff like this happens all the time~
i dont know if you have noticed but even the rinnegans riges now are still unequal pay close attention. that picture was from one of the last scenes in the original naruto it was before shippuden and DINIVIS can back me up.thank you for your time.
This version of rinnegan was never shown in the original anime, it was strictly shippuden. There was one image of pain's eyes in part one, but it looked like a normal pair of eyes and nothing like this.
This was the first version of Pain's rinnegan, the anime was following the manga exactly. It was only later on in shippuden that Kishi changed it to its final version.
anime tries to use visual impact in a few frames that would drive the manga pages to to many frames just to get the same results as in anime, thats the beauty of anime over drawings the impact produce. If Naruto was a book no pictures at all Kishi would have to wright long sentences to describe the effect to get the reader reaction that a few frames of anime dose.