^Probably because horny guys like inserting themselves into the protags, which is why they usually have literally no personality.
I personally dislike self-inserts, especially if they have some bullshitty thing that makes them special and/or the girls like them for literally no reason.
And cases like the Idolmaster Producer where you're told you have certain abilities or talents (instead of cases like Pokemon where you develop your abilities, and even if a character likes you, you get proper development from them).