I wear my badge ONLY in badge attire. While in such attire, I have worn my badge to church, political shindigs/fundraisers, weddings, and funerals.
On Founders' Day, I make sure to dress up no matter what I am doing that day. I just make sure to be in badge attire.
I did wear mine at my wedding. (Since I have the ZTA badge with pearls and sapphires, it was my 'something blue'.)
IMO, badges should only be worn when in proper attire. But, once again, that may just be the 'Southern belle' in me.