Oh I don't know Willy ,waking up after a late night's of drinking the sogginess of the cold pizza adds to the texture feel of your mouth to create a culinary cacophony that seems to work at a fundamental level.
Heating it up seems to be an undeserved indulgence that reinforces the previous night's behavior and could lead to life long imperilment .
Try eastings cold pizza i, you will find it out to be a character building exercise .
I have been easting cold pizza all my life, and I am sure you will agree that no one is more of a character than me.