Freestyle and folkstyle wrestling are the most popular grappling systems today.
This is one of the biggest misconceptions of what happened on the battlefields before firearms came into existence.IMO Wing chun doesnt have ground work because on the battlefield going to the ground would mean death.
Grab some weapons, put on some armor and grab about 60 guys to go 30 on 30. You will find that, just as often as not, people end up grappling on the ground.
As far as using WC principles on the ground, that is about as ludicrous as saying you can use ground principles in the standing realm.