I still think asm is essential to know. And I'm not even an old fart. Knowing assembly makes it far easier to rationalize about what my C programs are doing, how things will perform, what the machine actually does, and so on, even up into my Ocaml code (which is what I tend to work in for much of my code these days).

Even C doesn't teach you about cache behavior, register spilling, calling conventions, and so on.

Plus, it helps to know assembly massively when you're in the embedded domain, or whenever you're close to the metal.