nice post and frankly it does not matter to me if he is the lead or not..his character is what matters and as of today he is the best male character in MB. I would any day prefer my heroine to be with such a character than with a hero/lead who is inhuman,ignorant,selfish,egoistic,brutal,mentally unstable,sadist etc etc..
The point is not really if he is lead or not, but how fandoms are handling his character..more than anything their insecurity of "their" hero is leading them to come up with some lame excuses to defend their hero by stating he is the lead at the end and not Sultan etc etc.. I cannot believe a punch in the story is taken so seriously..When Sultan pointed gun at RK-how dare he?..when RK punches Sultan-he is my hero!..When Sultan tries to save Madhu or frankly try to make sure she is fine-how dare he interfere?..When RK forcefully takes Madhu and handcuffs her like an animal-he is just scared to lose her!!..LOL..I appreciate people loving an actor/character extremely but expect them to not defend their loved character's insanity as expression of love!..
Story is what will decide if Madhu will go with RK or will there be a Sultan-Madhu angle and not us..AS you rightly said Madhu is the central character and it is her journey we are watching. All characters are important in a story whether they are the lead or not.