Erm, I get where you are coming from and, true, it is okay to try and get the most out of every character. But the very first panel of him appearing is him physically hurting MC, lmao. Saying he never hit MC is plaing wrong. There also is a not small amount of incredibly heavy mental abuse.
He pushed him, he didn't hit him. He has never once gotten physically violent with him (that we saw). He's literally just using basic scare tactics (pushing, yelling, acting tough, intimidation, etc.) to get his objective. As a bully he's a really really bad one. A proper shake down wouldn't involve a simple push and some yelling. And the fact he justifies not hitting him because of school rules, when a bully would at the very least get somewhat physically violent, shows that he does not want to cross a certain line. His actions make no sense otherwise.
Yes this is psychological abuse, yes this is still violent and not at all acceptable, but what I mean to say is that from the very start the manga wanted to present this bully as someone who has something more going on (which we're now going to get into), and we really shouldn't be surprised that he has a proper backstory. He was not presented as a one-dimensional tool as you say, he's literally meant to be an important part of the story.
If he was just meant to be an average evil bully the manga wouldn't have taken the care to explain minor details such as him not actually pushing Yuushin down the stairs, or him and Yuushin having been good friends until a very specific point in time. It's clear the manga is heading not necessarily into his redemption arc, but at the very least towards integrating him as a character in the story.
Basically I think people should wait and see what happens and passing all this judgement early on feels unjustified. And I say all this as someone who was heavily bullied in school too, trust me I don't sympathize with bullies easily. But I know some people will just never forgive the guy and don't care to have him develop a character. Me, I'm just curious to how he fits in the overall narrative.