the Allies could have kept fire bombing cities and it would’ve caused far more deaths

This is an underappreciated fact. I grew up in U.S. public schools learning in elementary school about the massive scale of destruction that atomic bombs did bring (and, well, the Cold War was still going at the time). We knew the words Hiroshima and Nagasaki very early on. But it wasn't until I was in college that I learned about the destructive scale of firebombing Japanese cities (and frankly, I learned it from a film class discussing Grave of the Fireflies, not from a history class).

And maybe I'm jaded because I'm a combat veteran who has seen firsthand the toll that an extended period of conventional warfare and insurgency brings on urban areas with millions of residents, but I don't think of nuclear war as really that big a departure from the shittiness of things that are actually within more recent memory. Or maybe that's a misconception I hold that should be corrected, and these anti-nuclear people are right to express concern about cultural attitudes towards nuclear weapons, I don't know.