I can think of a couple reasons.Hobie-wan wrote: The real question is why didn't they just let you use the Select Game switch on the console to cycle through them.
1) If these are straight copies of the originals (and I have no reason to think otherwise) they want to keep all of the switches on the console operating as the original.
2) (More important) If I had to guess, the toggle switches are actually setting address lines on a 16K rom in the cart. This would allow them to simply do a bit-for bit copy of 8 2K games in sequence and still have the cart look completely natural to the console. Otherwise, they'd have to install some means of bank switching on the cart, along with some software control. It really is a lot easier.
