its not wrong to like straight stuff, its just...... you have so much of it. so so much. webcomics are created independently, giving people a lot more free reign on what they can say and do in them, and while networks and publishers and maybe even viewers of mainstream media want straight stories, very few webcomic producers and fans do. most of us are lgbt (or straight girls with a fetish for BL, but i try to ignore them) so why wouldnt we tell stories that reflect us?
that being said, there are successful, high quality webcomics following heterosexual romance. plenty of them. maybe youre just so unused to lgbt content, youre exaggerating how much there is?