Hi, I have the medium tote from the flight collection. I keep the rubbery thingy on. I think it looks adorable on the bag. My gf has the small pouchette and she keeps the rubbery thingy on as well. I don't think its meant to be taken off or it could just be a personal preference thing.
hmmm ive just bought my dior flight in bleu marine... and was thinking about the rubber thing too..anyhow, it probably looks cool as to where it already is!