I used to use it for taking quick notes when I had a slow computer. I didn't want to wait for Word to load, so I'd just use Notepad. Now I use Post Its or just don't write stuff down as much.
Funny enough, I use it like a notepad. Oh s***, I need to write this down real quick. I need to grab an exerpt off a website, our store serial number or make a quick list. It's literally scrap paper in digital form for me.
Just because it's portable doesn't necessarily mean that it's allowed on the organizations allow list, but it does seem highly unlikely that the organization doesn't have any alternative text editors allowed.
But maybe they don't edit text files often enough to bother. And honestly, notepad was recently updated with tabs which makes it a lot more usable that it used to be.
I use it all the time for quick notes at work, with its very simple interface, and the tabs feature was a game changer. Especially useful for phone calls in my case, although my typing speed far exceeds my writing speed so maybe I'm the exception because of that.
I don't use it to program though, usually that's delegated to Visual Studio.
I use it as a cache for chunks of text I want to move around. I use Textpad a lot for code and config files where I don't need all the lookup and predictive stuff.
I prefer having a bare-bones text editor over anything with formatting. Most of the time, I don't want the formatting to carry over, I want it stripped down to just the content, just the text. Word can get annoying sometimes when you're trying to copy and paste and it does something stupid like carrying over weird frames or tables or whatever the hell. That said, I'll still use a "fancy" text editor like Notepad++ or Sublime Text.