Agree.
I think he was brought on board MB by the Channel in the hope that his character would eventually grow into a poweful one overshadowing both RK and MB.
Channel probably thought that a negative RK would drive viewers to Sultan. A few did. But the majority loved RK bcos of his unique characterisation so far unseen in Hindi Telly,
On the other hand Sultan character just could not make the desired impact with the majority. He was seen as an irritant in the relations between RK and Madhu,
Now Sultan's character is turning negative. The audience may tolerate him in a negative role but that hardly provides much needed recognition for an actor as the character of Sultan has become a disliked one.
Unlike Dipalis which is hated but also respected for the actresses acting skills. On the other hand Sultan garners hate on both counts, for the character as well as the wooden acting.
Hence no point sticking with a role that doesnt benefit or fit you by any yardstick.