It's a lot more feature filled and frankly not very nice looking if all you want is a simple replacement for Notepad. Notepads (with an s) is much better imo.
Your first two points are part of Notepad now too. Everything else you've said is true though, including the find and replace function supporting regex. It's amazingly powerful for editing.
It also supports line numbering, which seems like a small thing but is really helpful.
+10000 for notepad++, its he swiss army knife of file editing tools.
Adding:
Plugins: CSV being read as a small dB table you can query is a game changer. Or have a JSON plugin that auto formats and queries as well as opens the JSON in a clickable nested window.
Pinned tabs: pin important tabs, I use one as a todo list.
Search for text within files in a folder: need to find a specific bit of text in one of dozens/hundreds/thousands/millions of files somewhere? Its lightning fast and works a treat
Search and replace with regex: amazing feature, use regex patterns to find complex parts of your files and replace them with something else
Bulk operations: remove newline, replace line breaks etc
Multi format support: see line breaks from different OSs like Unix and windows and amend them
Portable install: you dont have to install it, you can use a portable version
Specifically: tabs, dark mode, and retention of unsaved documents. They're apps for very different purposes, but Notepad has had some nice little updates over recent years.
Notepad++ isn't trying to shoehorn in AI for starters. It's clear Microsoft is praying the current gimmicky narrative of AI will let the masses not realize this is a privacy nightmare.
the only thing I need it for is to select text vertically (by holding left alt). there are a few similar ones for linux but some crash and the rest don't have a dark theme, so I still use it with wine.
Yes, it objectively is. And so are various other text editor options that are out there.
But just speaking about Notepad++, you can scale it down to a very simple text editor (like Notepad), it you can easily ramp it up to a much more feature rich one. And for me, the ability to have a vertical list of files is a big plus. As is its ability to optionally show line numbers.