Yeah this feels like the editor saw it and went "Who's supposed to be the self insert here?" And we're all slightly worse of for it as a result.
I agree. While the current premise is not BAD (though I've come close to dropping this series a few times already because of the constant waves of tired cliches and tropes), it is depressing and telling that the editor rejected the mangaka's original idea. Sure, the "delinquent boy gets teased by a "I can fix him" honor student girl" setup isn't that original, but originality clearly wasn't the main problem, considering that what we have now instead is even more cliche. It definitely feels like the main problem was how "relatable" it would be for their primary target demographic.
The manga industry generally seems to have this problem of pushing one or two kinds of works. One is something extremely safe and on-trend like this or other self-insert high school romcoms (or isekai setups). Something that they can safely market and sell with low risk, and maybe get a few rare hits.
The other thing is kind of the opposite, where they want stuff with really punchy and eye-catching and provocative setups. Shonen Jump in particular does this a lot. And what ends up happening with those series is that they get caught in this loop of being expected to constantly keep things fresh and exciting, but also keep going as long as possible to milk as much money for the publisher as they can, almost inevitably crashing and burning by the end. But it's still considered a success since they've already made their money, even if the final product and ending are disappointing.
Both feel like pretty short-sighted ways of overly restricting creators from just making what they want to make, and it results in a lot of cookie cutter stuff, and/or cool ideas getting run into the ground as they get dragged out. Sometimes, good stuff is still made within these constraints, but it's hard not to imagine what we could have if editorial stopped breathing down creators' necks quite so aggressively, and let them cook from time to time.