I don't think it is a case close-mindedness or "seeing it a billion times in seinen already". Alot of seinen have "those scenes", but they are just there for eye-candy and rarely important to the plot at all. Usually, it doesn't really hit so close to reality
I think the problem is that it's just like a bolt out of the blue from nowhere, especially people who picked up the series around chapter 6. Many people didn't expect a development like this, and are floored by it. So in a sense, it is a kind of "Shocking Swerve". But its a smart move, alluding to it will probably be a good way to test fan reaction early, rather than have it drop like an anvil when the series progresses further (possibly breaking the fanbase in two). There are just too many details that are unclear to really understand what really happened. So its a plot hook of sorts.
I never understood the backlash (there wasn't much of one in the earlier case. The other one...on the other hand...), since most of the longer time fans have already wonderd what was up with Yuki since Day 1. It is to be expected she has some kind of unusual experience or reasons (early on the "School Days" thing is being throw around alot) behind her helping Utsumi.
As for a certain someone's situation...
In a weird way, people caring about what happened to Utsumi (and the girls) indicates that the characters are likable and people actually care about them. So bizarrely, the rage is a form of love IMHO.