I'm a little late to the party, but something I've come realize recently is that my affection towards CLI applications comes from the fact that I usually don't have to take my hands off the keyboard.
Human hands can move very fast, faster than we can assemble cogent thoughts thanks to muscle memory (and other things that I'm sure I'm not aware of). I don't know if this is a universal thing, but I like it when I don't have to think about how to get something done. I consciously picture the end goal in my mind, and my hands just do.
Of course, I'm a sloppy typist, and still relatively unrehearsed when it comes to working with Vim and friends. But I've been most of the standard GNU applications long enough to realize that my brain no longer directs my hands to interact with the keyboard for frequent simple tasks (generate a line plot for this two column CSV, use awk to get the penultimate column of this file, hash files in a directory to remove duplicates, open HN in a browser...).
I'm also a big sucker for working with programs that compose well with other programs. If I had all the time and money in the world, I'd love to have more GUI apps that explored GUI/CLI interop better. I think one example many developers can comment on is how nice it is when you can combine CLI git commands with git in your code editor. Sometimes, it's just easier to resolve ugly merge conflicts with a GUI. Or there's a really weird command that doesn't exist in your GUI so you need to type it out on the commandline.
There's definitely a lot more work to be done in this domain and I'm excited to see how software/OS/library developers explore this in years to come.