Because agreeing to become Seymour's doll is apparently the universally agreed upon outcome huh?
Lena only loses her "challenge" if you don't care about her independence, Ian can just as easily coast through his story since his economical situation is much less dire in the first place. You also ignored the whole Lena music thing. I think both MC's have a good variety content the main difference is that one of Lena's expressive avenues is selling her body for thirst online rather than boxing with the bros.
This argument is silly, the game would have been simpler to develop with only Ian, sure, the same is true for Lena though so it's not really a interesting subject. We have the game in this form and will have to take it for what it's worth. You prefer Ian, fair enough, that doesn't mean the game would be any interesting if we only played as him.