Pasting objects into text files is pretty disruptive

It's still text with some formatting underneath, though, just like HTML. Actually, in HTML we already have it in form of contenteditable attribute. You can straight up paste images and move other html elements into elements with it. I just checked, you can even do this with full on canvas elements and animated webgl views if you wanted to for some reason, though the code must be adjusted to account for it. I have yet to see it being useful and not a liability, though.