Playing devil's advocate: a fiber+power cable makes some sense. The main thing which limits the cable length is the data wires, not the power wires (just notice how one of the main counter-arguments for "one USB cable to rule them all" is "the higher bandwidth passive USB cables have to be shorter and thicker").
Fiber is far too fragile to deal with the abuse even babied USB cables put up with, unless you mandate some kind of semi-articulating steel conduit anyway.
Considering recycling is stupidly uneconomic for all but a tiny selection of materials and just makes the whole carbon issue even worse, why would we do that?
Hell, for plastic throwing it in a landfill is only second best to never making it in the first place.
I'd probably guess it's too expensive? IIRC the original Thunderbolt spec was a fiber standard and they moved it to copper because people wanted to power stuff and adding copper cabling for power + power negotiation was infeasible cost wise so they ended up with a copper only cabling solution instead.
