Well I don’t think anyone would truly *need* water at a certain temperature and not too sure as to why you’d need a specified amount at said temp...
Having said that, I am heavily into my “posh” loose teas and certain of those are better at certain temperatures..
Black tea needs the water to be fully boiling 100c - but some more delicate teas, such as some green and white teas etc, are better at 80c or they go bitter/burnt as well other variations.
Plus they do say as above that boiling water isn’t good for coffee with
it..
However you don’t really a specialist appliance for it and you can get much cheaper kettles with the feature - plus I dare say a lot of people wouldn’t care about the subtleties anyway!