1944 is kind of a slow creep.
You asked me if I favored executing 14-year-olds, and I pointed out that this was a silly premise. The case discussed here involved a murder committed at 17.
I don't see this particular Supreme Court case as a major problem, myself. I don't think society is going to hell because we can't sentence teenagers to death. Tried as adults for other sentences is a separate issue.
However, I am concerned at the tendency of the increasingly arbitrary opinions of nine justices being set up as the law of the land, overruling states, voters, and all the rest.
Remember, a "living" Constitution can be taken in two directions.