Purely aesthetics! ;) I wouldn't want to mess up a good thing. You would just have a positive and a negative way of writing the same thing.

You could turn the paren bubbles inside-out like )foo )bar(( but that doesn't look as cool to me as flipping the ramps upside-down like /foo /bar\\ and \foo \bar//.

It would give the kids something to keep bikeshedding about, and spawn 20 different code style standards and associated autoformatters. All of that pointless, but hopefully, such injection of energy into the ecosystem would help Lisp get more popular.