I kinda just really realized that each pair of sharingan specializes in one specific jutsu. Some might come with more jutsu than others but there is always this one jutsu that defines the user. At least that's what i noticed kishi tries to do. Here are a few sharingan jutsu's that pretty much defined their users..
Obito: Kamui (his eyes are, overall, the key to another dimension entirely)
And Sasuke........ Amaterasu
..Maybe it's not sasuke's path to achieve the perfect susano because he has shown higher mastery with amaterasu than any uchiha.
1. When raikage was fighting sasuke, instead of sasuke's susanno growing even more, instead his mastery with amaterasu kept growing, he went from cloaking his susanno with amaterasu to completely taking it to the next level with it when raikage was about to drop kick him, some blaze release amaterasu technique, i dont remember the name -.- ...but yea he chose that instead of strengthening his susanno
2. When sasuke achieved EMS, yes his susanno did change appearance but most importantly he acquired the amaterasu sword called kagutsuchi, both as a sword and as a blaze release in the same hand. Plus his susanno, shoots amaterasu arrows.
Sasuke's path seems to set down amaterasu while madara on the other hand was a beast with his susanno. Just the appearance alone protects his front and back, his susanno summons meteors, his susanno is able to become perfect. While fighting hashirama, he manipulates the shape of it till it's armor for the kyuubi while sasuke specializes in manipulating the shape of amaterasu to his will. Get what i mean? Im thinking maybe kishi tries to show that madara's specialty is susanno while sasuke's is amaterasu.. which MIGHT decrease sasuke's susanno from becoming perfect or being as strong.
...Or i could be wrong, lol discuss.