As a developer, why the hell do I need stylized text when I'm having a user fill out, say, a shipping form? Why should I have to worry about whether someone applied italics to their zip code? Should I really have to try to make the thermal label printer print out Zapf Dingbats if someone pastes that in there?

Also, forms go far beyond text input. Are you seriously suggesting that dropdown menus, multi-select boxes, sliders, radio buttons, datepickers, etc. should all be reimplemented on top of a rich text element?