Sweeter than cold milk in hot tea. When you simmer milk, it becomes sweeter. I don't know the science behind it, but it tastes sweeter to me. Gives the tea or in your case, the coffee, a richer taste. I rarely take milk or cream in my tea. You have to get the portion just right with tea. Under milk or cream it, and it looks incredibly vile and tastes a bit strange. Over milk or cream it, and you can't taste the tea. Get it just right and it's lovely. Truly a first world problem.
Don't even get me started on people who put milk or cream first, then the tea. Stark raving lunatics!
Or as dear jkcerda says, "Jail them!

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