During the trial it was revealed that McDonald’s knew that heating their coffee to this temperature would be dangerous, but they did it anyways because it would save them money. When you serve coffee that is too hot to drink, it will take much longer for a person to drink their coffee, which means that McDonald’s will not have to give out as many free refills of coffee. This policy by the fast food chain is the reason the jury awarded $2.7 million dollars in punitive damages in the McDonald's hot coffee case. Punitive damages are meant to punish the defendant for their inappropriate business practice.
Oh man there is so much to this case. First, she asked for like $40k, enough to cover the cost of the medical bills. To be clear, she received extensive burns as the coffee was so hot that it would burn in seconds (the wiki had a breakdown of the times/temps and they were illuminating). Moreover, it wasn’t even the hottest coffee available. Starbucks was serving much hotter coffee at the time (the hottest I think recorded). In the end, she got paid, but McDs never cooled their coffee (nor did anyone else), all they did was make better lids lol.
And you're right that it didn't change coffee temps that much:
“During the Liebeck court proceedings, McDonald’s said it served its coffee between 180 and 190 degrees,” according to The New York Times. “The company has refused to disclose today’s standard temperature, but Retro Report shows a handbook for franchisees calling for temperatures 10 degrees lower.”
If it doesn’t sound like much, it’s because it’s not. McDonald’s chooses to keep their coffee scaldingly hot because, according to attorney Butch Wagner, hot coffee stays fresh for longer. They save money by doing this (millions per day, in fact, across their US franchises alone), even if it means paying out for other hot coffee settlements—of which there are plenty.