Cork handles are nothing new, but you just don't see it much on custom knives these days. There are factory knife companies that still use it. They also use it a lot on fishing rods handles.
The trends seem to be more towards synthetics and treated materials.
Natural cork has some amazing properties. There is nothing like it! They do make sealers for it, but they spoil some of the natural properties, like the non-slip wet grip. All they really do is prevent the cork from "patina" and make it easier to clean.
... just Google, "properties of natural cork",... very durable, shock absorbent, lightweight, doesn't shrink or crack, biostatic, impermeable, fire retardant, low heat conductivity (never gets too hot or too cold), UV resistant and on and on...
Cork is a bit of a culture shock for some,... but it brings a lot to the table in terms of functionality and performance.
Of course, you can ding it, scratch it etc., if you abuse it, like any other material. It is what it is, cork.
However, if you just use it to hold the blade by, which is what knife handles are for,… it is the most awesome!