It's a nice little command that can help to see if you have lag, but there's not really much of a point to it. We already have /care, which does the same job as ping but gives a nicer message, so I honestly don't think we need /ping.
There's a command on Rituals of Fire called /lag that tells you how the server's doing. It's similar to /ping and /care but shows you a level on how good the connection is. 20tps is the best whereas anything lower is bad.