One assumes anyone who actually needs their glasses (ie: can't see shit without them) would know better than to store them in a case that offers zero protection against catastrophic breakage.
On the other hand, if you merely wear fashion sunglasses, and have eighty-dollars to piss away (as opposed to just using the case your shades already came with) these should fit the bill.
These look interesting but thee does not appear to be a liner of any sort. I would be concerned about the leather inside basically rubbing against the lens of my expensive glasses over time
Aside from the lenses, a lot of "plastic" frames are vegetable acetate, which is a nice material but prone to instability over the long term. Skin oils, relative humidity, and other factors contribute to bubbling and that milky fading you sometimes see. So I wouldn’t want it rubbing up against another non-inert material.