Neither, or both. Back in the early 1960's, my mom would make little stuffed meatlaofs and giant stuffed burger patties. They were delicious then and I like them now. She rarely did cheese on the inside, as she felt it was better on the outside (she preferred two thick, hand cut slices of cheddar).
Juicy Lucy...MOINK...same concept, a cute name, and some good fun for a concept that has been around a long time. Cook what you enjoy, have fun with it.
They'll be around a long time, it isn't a fad.
on edit: I actually prefer my burgers to be medium rare and have found that to achieve that, I can't stuff them, the filling never heats up enough.
