Is it remarkable because of how rare it is for admittedly insufficient disposable coffee cups to negligently discharge their contents all over their users, or because of how rare it is that such discharge results in life-threatening injuries and years of reconstructive treatment to try to repair destroyed genitals?

Yes, people take care with dangerous/messy things. Is any possible source of danger to be considered a problem to be eliminated? If that's what you're after, please go join an appropriate lifestyle community, as your desire is an abstracted fantasy incongruent with reality.

The case isn't remarkable because she got third-degree burns all over her legs and genitals, it's remarkable because McDonalds didn't settle out of court like in the hundreds of other similar lawsuits against them around the same time period. (And this was after they'd received a number of warnings that their coffee was unsafe too.)