There was an annoying copy-and-paste notification in earlier iOSs, too. It made no sense. If I copy text from one app and then paste it into another, I know what I’m doing and don't need a prompt. That eventually got dropped.
What concerns me is that ANY app could ever access the clipboard WITHOUT my permission. It should NEVER happen.
No app should be able to read the clipboard willy-nilly without user action, decision, or intervention. I may have copied financial data, medical information, passwords, or personal, private messages from one place to another, even within an app, say, Pages. That content should NEVER be available at any point to another app without my taking an action to paste it. No app should be able to scan, read, and use the contents of my clipboard.
Otherwise, things are ripe for hacking, identity theft, and password stealing.