Removing the center of the pin detracts from the symbology.I have a flag pin in mine simply because I want to own it for more than the 30 minutes it takes for the normal ones to fall out somewhere on the ground. A pin secures it nicely for the 2 weeks prior to 11/11.
Remember when the centers were mainly green and just a few were black?
Green centers were made by surviving veterans and their families.
Black ones were made by widows of soldiers and their families.