I just showed a picture to my girlfriend and she cringed. So now I definitely need to get a pair.
Opera pumps are the correct shoe for white tie and optional for black tie. It is the only remaining item of clothing in formal dress that hasn't changed since its (alleged) introduction by Brummell which for all ye faithful gentlemen of sartorialism holds a deep symbolic affection and nod to continuous style and heritage as well as a direct link to the past. For those who wear breeches with white tie as part of alternative court dress in the UK, they are the only acceptable shoe.
Also, it has to have a bow, or it isn't a proper opera pump (in fact, a lace-up would look better, especially with ribbon laces).
They are not everyone's cup of tea, hence why Oxfords are also acceptable for white and black tie. One should not begrudge those who choose to wear opera pumps. Having such a choice is what makes formal dress exciting and stops it from being cake-mould cookie-cutter everyone-in-the-same-shoes boringness, etc.