I'm not surprised your wife doesn't want to go to this fancy dress themed wedding.
If the Best Man doesn't get up to do his speech in a green mask and hat he's missing a trick.
For what it's worth it sounds like the bride wants to invite accessories to her day, rather than guests, and it could turn out to be nothing more than a well orchestrated photoshoot with some wedding bits in between.
Some brides want to plan every last detail for their day, the one thing they forget about is love and joy. Suppose that doesn't matter though as long as it looks nice on instagram.