If all you do in your job is write JS, that is fantastic and you are awesome, just like all the people that write CSS or have a focus in a particular area like accessibility, SVG, animation etc.
What I am very concerned about is that many still don’t see value in being skilled in CSS & HTML. This attitude is something I just don’t understand. All of us working together provide value in our industry.
+1 on all Mandy’s points.
I suspect HTML and CSS skill will swing back higher in desirability a bit as design trends swing toward more complicated looks. More interesting layouts being one of those things. I tend to find those developers who only dabble in HTML/CSS fall over quickly when it comes to from-scratch work that involves layout. There is a lot of gray area here too. For example, I write Ruby code, but I fall over quickly when it comes to even moderately complex things.