It's either his haters that like to talk trash about him or his fans that mostly talk about him.
He keeps the story going forward in an unexpected interesting way.
Point being, did anyone predict that Sasuke was going to absorb Orochimaru?
Did anyone predict that Sasuke was going to find new teammates to help him achieve his goal of killing his brother?
Did anyone predict that Sasuke was going to initiate an attack on Konoha?
Did anyone predict that Sasuke was going to charge a Chidori and almost kill Sakura twice?
Did anyone predict that Sasuke was going to spare the Leaf and help the SA?
Did anyone predict that Sasuke was going to announce that he would be the one to become Hokage?
Did anyone predict that Sasuke was going to capture all the Tailed Beasts in mini CT's?
Did anyone predict that Sasuke would say that he's going to be the one who takes in all the darkness and hatred and fight it head on?
More than half of you probably didn't even think that Sasuke would do this, and yet you call him boring? Lol
The problem with Sasuke is that he is always changing and that's what makes him the hot topic. With Naruto, you know exactly what his purpose is, you know exactly what he is going to do, you know exactly what he is fighting for, and you know exactly why he is doing what he is doing.
If Sasuke stayed in the village and acted like Naruto then he would be just like Kakashi who is just "tagging along" whenever there is trouble, and that's boring.
This is exactly why more people tend to talk about Vegeta more than Goku. Goku's character was the main hero who was expected to do good and save the earth from villains and aliens, but what people enjoyed the most was Vegeta's introduction at trying to kill the earth and then later on in the Frieza arc, he showed emotion towards Goku about his home planet and defeating Frieza, and then later on he became a little closer and started a family towards the Cell Saga.
No one actually cares about Goku's character. They only care about him because of his power.
People actually care about Vegeta's character, his attitude and his personality. They just don't look at his power because their is more to look at when it comes to Vegeta, so I figure that the same can be said for Sasuke.
Once Sasuke starts a new goal and then finishes it, he tries to find a new one and that can open up more paths to what his purpose is. Sasuke doesn't stand still, nor does he stop. He keeps moving and whether he is playing on the dark side or the good side, he is always changing.