Re: "text editor" - for at least 5 years now, & probably longer than that, CSS coding tools have been providing text editor
plus auto-generation of code snippets;
plus preview functions, etc. So when you say "text editor," it's not like having to go in there with a bare-bones editor like vim with a CSS reference book at your side.
Even so things have changed over the years & the need to know CSS just to build a basic site has grown considerably less. I used to build HTML & CSS "by hand" way back around 2000 or so; back then you had to do browser tests & hacks to get everything to more or less work. Starting around 2005 I got heavily into WordPress and started doing CSS with dedicated tools. But these days, it's amazing how well something like SquareSpace or Weebly works if all you want to do is get a blog or forum or small business site up quickly. Sure, if you are a coder at heart, I don't imagine you'd ever want to lose sight of the code completely; but for some of us today, web sites have become similar to light switches: we don't need to know how electricity works to illuminate the room.
Of course automation of CSS has begat its share of poor outcomes - e.g. it is fairly often that I find a page on a site I'd like to print out; go to print, and you discover no one bothered to set up the template for that & the default template does not print at all nicely. Or no one set up the template for mobile, etc. Also most templates are designed with decent adherence to usability guidelines, but if you don't know why usability matters you can still muck things up.
So back to your question - if you find yourself asking, as you have, "is it worth learning CSS?" than most likely the answer is "probably not right now"; otherwise you'd already know the answer. The exceptions typically are 1) you love to code and/or want a job that requires CSS knowledge (e.g. something to do with web design), or 2) as
@Student100 has pointed out, you need to go beyond available templates.
The other thing is - and this is irrespective of which tools you use - if you've never built a website before, it's worth learning about design conventions, especially for usability, a.k.a.
"user experience" (UX). I'm not that active anymore in design so I don't know how standards may have shifted, but a book like Steve Krug's
Don't Make Me Think was very handy in its day. A
https://www.amazon.com/dp/0321965515/?tag=pfamazon01-20 was published in 2014 and that seems recent enough to still be valid. Web design is not about how pretty you can make something, it's about how well a site serves the shared goals of its owners & its users.