I'm finding when laying out tabular data that it's a pain to add/edit tab stops only from the small text input field (some of the UX there isn't really good either, as I can't seem to scroll down the window when I have entered more than 5 tab stops).
Being able to see the tab stops on a ruler (similar to InDesign) to be able to click and drag them to adjust would make viewing and adjusting the paragraph tab stops a million times better.