See, to me, the issue wasn't the killing off of or maiming of characters. But it was the failure to follow up on it meaningfully. There's no real examination of the characters reacting to the Fall of Beacon, the death of people they knew or Yang losing her arm. It doesn't carry near the weight it should.
What we do get is rushed and half-assed- not to mention the various retcons that got crammed in to appeal to a vocal minority of shippers. Not to mention the fact that JNR takes exactly the wrong lesson from Pyrrha's death and that Penny gets brought back...only to kill her off again. There's the hack-job villainization for Ironwood because of reasons, Cinder's rather lackluster back story. The fact that Salem is literally Ozpin's evil ex-wife with the motivation of a bad shonen villain, with the former being something I remember people JOKING about as a possibility prior to that reveal and the Emerald's half-ass 'redemption'.
The show just kept adding more and more characters to the main team instead of focusing more on the ones we already had. Why even add Maria when you could have had Qrow (or Ospin, if you really want to include Oscar) teaching RWBY about the Silver Eyes? Why not have Ruby actually have to struggle and practice to learn how to use them instead of just being a super-weapon that naturally conforms to her existing personality? Why even have JNR stick around past V5? Sending them to Vacuo to help guard the Relic there would have been a great way to meaningfully get them out of the story. And I could go on for days about how the characterization of the main characters has been dulled and smoothed, removing much of what made them interesting to watch.
On a final note, one of my biggest issues was how instead of the characters getting stronger as the series goes on, the world just got weaker so they'd have an easier time. Not to mention the hilariously bad issue RWBY-the-show-has with show-don't-tell. And, at least to me, that when the show should have used the opportunity to wow us as the setting opened up and we left Beacon, Remant feels... empty and bland.