Not sure if it's a modern feature per se. But if you have a tankless heater, you can set the temperature to be a little bit above the hottest water you require. If you have a heater with a tank, you need to keep it hot enough to prevent bacterial growth, specifically those that cause legionnaire's disease.

I've seen systems with a tank, heat pump and solar panels, where the system automagically drives up the temperature to kill bacteria every once in a while. Supposedly that's more efficient than keeping it hot all the time.

Its complicated, as at first you ran as how as you could to maximize the amount of hot water you had, then there was a period where it was seen as more energy efficient and prevented burns running at lower temperatures. "Modern" practice in this case started somewhere around 1970 where you have a termostatic valve (also called a Tempered Water System) to regulate the temperature of the resulting hot water to non-scalding levels.