The problem is that they are fiberglass, and small particles (And of course passing birds) striking them erode the leading edge. I would think that they could fabricate a lightweight replaceable metal bull nose (Maybe ultra lite titanium or scandium aluminum alloy ) on the propeller's leading edge and continue to use them there being no recyclable market for shredded epoxy fiberglass.
(Of course, there is the other question of whether we should be using these overpriced monstrosities at all.)