Let the hive mind of Engadget get that for you.
"I just moved into a new apartment and have been reading about all of the new power strips out there, especially the green ones. I was wondering if you had any suggestions about which "green "power strips are out there with decent joules ratings. And when I say green, I mean power strips that have the remotes or switches to turn off all electricity flowing to certain plugs and with at least 2 plugs that are always on. I was looking specifically at sub $50 because I will need two, but if that is not possible I could be convinced otherwise. Thanks!"
Well, I don't know much about Slingbox, but you brought up game consoles. Xbox 360 for example is a console that generates a lot of heat, and it needs good ventilation or it can potentially overheat and destroy components. And a lot of these set-top boxes have harddrives in them for dvr and overheating those can destroy the harddrives. So yes, the design may have a little to a do with marketing too, but I'm sure that at least a small part of the design is to discourage stacking to protect the components in these devices and ensure stability.