Except we already have an NPC version of Ian (via Lena's POV), and he's nothing like a wannabe player that Jeremy is. Ian is first and foremost, a wannabe writer, who has a wide social network with his friends who he constantly interacts with, he has different ambitions (and struggles along the way) that define him. Sure, the heart-break might make him act more like a player, but he wouldn't be a jerk about it.
What do we gain with Jeremy as a protagonist? A typical protagonist of a porn game whose sole focus is to bang as many girls as possible, while also trying to win the MMA tournament. That's just not enough to make him compelling. Even if we get to the bottom of his insecurities, we still don't know his true aspirations, whether he likes anything beside sport, whether he has any good friends other than Ian and Billy, how does that friendship affect him (that has nothing to do with girl sharing). He's too cool for Perry and Wade, kinda ignores Emma (unless he wants to fuck her) and is kinda fixated on Ivy. If he was a player character, he'd probably get in contact with Axel, but then what? Where does his character go? What challenges does he face aside from Ivy cockblocking him from time to time? Does he face racism when trying to apply for jobs in a different field? So far, none of these questions have an answer. And without those answers, Jeremy wouldn't become a better character simply because you could play as him.