I remember we were having a large collaborative work session on modular footwear, this was about 10 years back. Most of us were hard at work cranking on different ways to have interchangable parts, when a designer who was smarter than me got up to leave the room. He left us with this, to paraphrase “I just realized this is futile, the entire shoe is a modular part of your wardrobe, if you wanted a different looking shoe, you would just buy another shoe. It is not like they cost as much as cars.”
The rest of us kept working, and a bunch of prototypes and samples were made, but nothing reached production.
I’ve seen a few zip products in production. They always fall apart for me in a couple of key areas: 1) zippers are fussy, they are never easy to zip on as they are to zip off. 2) Shoes get grimy, I really don’t want to be touching the bottom of my shoes much.