I've been thinking about draggable column widths and what I would do in the case of resizing the table width wise is let you specify 1 column with a dynamic width. That would be, by far, the easiest and least destructive method of implementing it.
Showing more rows for vertical resizing also seems doable.
Its doable until you start to realize you need more than 100 lines of code for the resizing grips, which has to take into account overall scale, the grip's scale, the parent's scale, the x/y offset, the minimum size of itself + neighbouring columns and code OnHide to stop moving the grip (because the parent can get hidden, say on ESC press), the resizing and reanchoring code for the text.
I know this firsthand after doing Omen3's vertical resizing grips.