I look up old iMessages, emails, group chat comments, and so forth constantly, often finding valuable gems of wit, reference-material, recommendations, or media that I dimly remember from years or even decades ago.

Signal and other messaging apps offer a 'search' bar across all sessions & history, so I doubt I'm the only one.

It's hard for me to imagine being so present-focused such a history wouldn't be personally useful.

Or, so worried about "someone [using] it against [me] in court" that I'd need more than the occasional auto-expiration, and specifically my messenger "protecting" me with intermittently-enforced loss-of-histories (on just theft/loss/hard-failure of primary device).

I have messages from a deceased friend. I find it comforting to read them from time to time.

Because of family phonos shared between me an my siblings, and between me and my wife.

All our communication is over signal, so it is a nice record to have.