> But I don't see how "AI writes a deeply personal letter for you" could possibly appeal to anyone.
Writing is hard, and the ideology of efficiency says it's always good automate hard things to make them easier.
Also, writing "deeply personal letters for others" was literally the dystopian job of the protagonist of Her, but at least his customers were better, in that they had the sense to hire an artist instead of using a bullshit machine AI.