Contrary to popular belief, edible panties are neither erotic, tasty, or fun. As someone who has actually had a girl wear these for me in real life once (though it was long, long ago), I can attest to the fact that these "toys" are not all they are cracked up to be.

First of all, real panties stretch around the bod of the wearer. Edible panties are one size fits all, and don't wrap nearly as nicely around your SO as the real thing. Also, because they are made of a flat, candy like substance, they aren't (or so I'm told) very comfortable. Their construction also makes them vulnerable to body heat, which causes them to start to melt, at least enough to become a sticky, gross, mess (assuming you've let them stay around that long!).

Finally, they really don't taste all that good, or feel too good against one's face, so the "edible" part of them sort of leaves a bit to be desired. Of course, YMMV.