@anon763
Yeah the original premise was going to feature two girls and Proto-Hitomi. Here's the thing, in that hypothetical story, the yuri would have development and any romance between the three leads would've been treated with some sincerity. In the manga we have now, the yuri wont amount to anything substantial. This new girl was introduced too late in the story and doesn't have a lot of screen time dedicated to her. Hitomi wont return her feelings, since she already likes the male lead.
At most, this delinquent will be a side character that acts like she's entitled to the Hitomi's attention and will treat the male lead like trash. And before the reader can say to themselves "Wait. Isn't this character kind of a jerk." the author will add some light yuri fanservice and the reader will suddenly forget that this character's kind of obnoxious. Why else do you think mangakas make these annoying obstacle characters women who like the female lead instead of men who like the female lead?
And to address the last point, no, the original premise is not inherently a "preferable" story. The manga would still be a Komi-san knockoff, only with a possible love triangle (which is "always fun" to watch), and girl-on-girl action. Would it still be a fun read, sure, but it wouldn't be an objective improvement of the manga we got now. In spite of what certain readers will say, making the leads in your romance manga all girls does make your story inherently superior to a romance between a guy and a girl (much like how a shoujou-ai/shonen-ai manga wouldn't get "better" if one of the character's genders was reversed so that the romance became a heterosexual one.).
@RandomPasserby
I'm not "offended" by yuri/yaoi. Some of my favorite manga/anime center around gay relationships. I hate when authors force a character whose sole prupose is to interfere with relationship of the romantic leads, regardless of gender/sexuality. The only reason why some readers defend this kind of obstacle characters is because they want to see yuri favservice, not yuri romance.