“Notice how the top of the Super NES doesn’t have a flat even surface like the NES? There are two good reasons for that. Lance explained in the same Nintendo Power article mentioned above that people don’t put bowls filled with cereal and milk or glasses of soda on curved surfaces. Spills were one of the primary service problems for the original NES( I’m sure no one reading this ever put food or drink anywhere near their NES deck). The ventilator vent was put into the back as opposed to on top for the same reason. The other reason for the curviness is that Lance wanted the SNES to have a sense of interactivity, meaning it’s something that is ok to touch and explore. In addition the bottom of the console was made flat so it could possibly be stacked onto other devices, such as the ill-fated Nintendo and Sony CD-Rom collaboration that never surfaced.”
— Playing with superpower.