The drawcard for me is that I can do in a few bytes of declarative CSS things that take many lines of imperative JS to get right, with fewer weird misbehaviours, fewer framework compatibility issues, and a lower time-to-interactive. Working under noscript conditions is just a cherry on the cake.
Deep down inside, however, I miss DSSSL.
It's moving in the right direction, but I'd still say that CSS has more quirks and misbehaviors than the common subset of JS...
The cost is increased complexity in both the CSS spec and browser implementations.
Old school flexing on us with the scheme. They don’t know about the sosofo!