It's great Ian has the MMA option, and you know... lots of people here seem to enjoy his play through enough. But when asking why the Ian play through gets hate... it's because the majority of players (irrespective of if he's a likable guy) can't wait for the Lena play through, bc that play through has story and teeth to it.
Lena's life and choices for her path of morality are intrinsically tied to her modeling, and sexuality.
I would love if EK upped Ian's cred in MMA and got to him to a level of status. And EK could have made him still a nice guy in those other roles, just within a job that actually moves the story along rather than diverting from it.
Sure, Ian gets laid, but no player of this game will ever read his book. The entire trope of very specifically, his job, takes away from the game play instead of adding to it.