Why do some foods taste better when they are hot while other foods taste better cold?
Why does temperature affect flavor?
When something is hot it makes certain flavors stronger while coldness make other flavors stronger. That's just how it is!
the senses on your toungue
It's because we are raised with certain expectations. Coffee is hot. Juice is cold. That's just what you expect, and what we teach our kids to expect.
It's generally because we're used to eating a certain food at a certain temperature. Many foods that we eat hot are preferred cold in other parts of the world. Likewise, many things we eat cold are eaten hot elsewhere.
I'm not sure what an accurate answer would be, but I know temperature effects texture also. Which also plays a part in what we consider appetizing.