Fiber optic is pretty fragile - far more so than a copper cable. Can't bend it past a certain radius, much less kink it.
Most copper data cables, including UTP, STP and co-ax react very poorly to sharp bends or kinking. If you take a Cat5 cable and kink it or stretch it, it's not going to work any more, at least not at Gbps rates.
Optical's main benefit is distance, not speed...
TOSlink and all that jazz worked because you connect stuff and that's it- the cable rarely gets disturbed. Think of your average business traveler - they'd go through optical cables like candy.
Good point, though I think the problem would more likely be the connector than the cable. Optical does not cope well with dust, grime etc.
This 100w power standard is pretty stupid, though. We're talking power levels where fires will definitely be possible from damaged USB cables.
Unless (and I have no idea if such is being implemented) a smart, bidirectional power protocol is in place that monitors the power sent vs the power received and shuts it down if there is a discrepancy---sort of like a super RCD.