What causes the Susano'o morph into more advanced stages?

Question

During Sasuke's "evil phase", the anime shows us his advancement along the different stages of the Susano'o. The most noticable thing is that Sasuke's Susano'o responds with his feelings, more like it feeds of his anger. During his fight with Danzo, Sasuke becomes really enraged at how Danzo talks about Itachi and his Susano'o starts developing flesh and its eyes light up. Later on in the fight, Sasuke screams and his Susano'o further develops an offensive weapon and even starts using arrows. (His Susano'o had 2 major powerups while he was against Danzo) [flesh and an offensive weapon]

During that moment, Obito even mentioned that "His hatred has matured and gained in power" (he says it a bit differently from how the manga does. Shippuden Episode 210).

So does this mean that the only way to advance the Susano'o is through negative emotions? I want to clarify this cause the Wiki doesn't explicitly state how the Susano'o morphs from bones to full clothed armor. The only Sharingan user that the anime really focuses on in terms of Susano'o development is Sasuke. So, its hard to actually generalize this concept of hatred feeding Susano'o for all Sharingan users. (I'm not sure if i missed something)

Answer 1

The hatred part was more of an exaggeration,which the Uchihas love to do(like Itachi and Obito).If that really was the case,how did Itachi become so powerful?He wasn't consumed by hatred.

Sasuke was only discovering and learning the powers of his Mangekyou Sharingan,which we know takes time.Although it is true that his negative emotions aka hatred forced him to use more chakra for his Sussano,thus giving him the complete "half" form.

After learning to activate this version,Sasuke never really needed to become that enraged before using it.

Most of the discoveries of the Mangekyou were by chance,just like Itachi did(Amaterasu Vs the fourth Mizukage)."Hatred" has nothing to do with it(only needed for activating the Mangekyou for the first time of course).