In this example, the poor readability is a feature. Nevertheless the ":" character is bash inner function, which tells the shell to do nothing (except the arguments expansion), like pass in python. This means that you can redefine it and use it to confuse others. Most of other special characters are not functions so you are not able to redefine them that easily.

And it's usually accompanied by the adjective "elegant", which I find rather baffling.

"Cute" or "cryptic", perhaps.