My problem with rich-text paste is that it transfers unwanted presentational formatting, resulting in mismatched fonts, sizes, and typography. I generally either want plain-text paste or preserving semantic elements (like bold/italic emphasis, links, and bullets).

More generally, when editing a document I want to be able to view both formatted text and "escaped" contents (like "view source"), and when copy-pasting or saving text, I want to be able to convert formatted text into "escaped" text to diff, and also paste text without misinterpreting asterisks and angle brackets as formatting information (until I explicitly copy text as source and paste as formatted).