You're able to disable the pin feature to prevent that data from being saved though, so it definitely isn't a requirement.
I'm also not sure where you've read that they collect the contents of messages, because as far as I'm aware they still aren't doing that and I can't find any info online that indicates that they are (other than their secure backup feature that's opt-in only I suppose)
This is actually a great point but for the opposite reason - if you ask a blind person if the night sky is beautiful, they would say they don't know because they've never seen it (they might add that they've heard other people describe it as such). Meanwhile, I just asked ChatGPT "Do you think the night sky is beautiful?" And it responded "Yes, I do..." and went on to explain why while describing senses its incapable of experiencing.
I'm also not sure where you've read that they collect the contents of messages, because as far as I'm aware they still aren't doing that and I can't find any info online that indicates that they are (other than their secure backup feature that's opt-in only I suppose)