You say that, but there are tons of features in Notes. They're just successfully kept out of your way until you go looking for them, so when you just want a note that's what you get. This is progressive disclosure, a longtime tenet of Apple GUI design.

A relevant and somewhat meta example: This year they added disclosable sections, which were previously a differentiator for Notion. That's in addition to handwriting selection and editing, voice memos, collaborative editing… Not to mention it's still a regular app and you can have as many note windows as you want.