the reason for the usb adaptors is simple.
everything in one nice little box.
to have all the consoles and carts, disks, to 1 TV is to massive
cords out the yingyang carts all over the floor, blowing off each cart only to have it to lock up in the middle of your game
I have most of my consoles hooked up to usb ( still need a turbo grafix)
I do not agree with arcade controlls to console
I have a Nintendo VS arcade with super Mario on it. I prefer the NES pad
do as I did. each birthday, Xmas, save a few dollars each payday and order one
with in a year and 1/2 I had most every one I want
I used a desk top case (looks better than a tower next to the DVD player, VCR, and satellite receiver)
2 usb hubs, all game pads in a cabnet allways hooked up
My N64 to USB is the one for PS1 also works just fine for me
My super NES are super smart joys from eBay came with new pads also
much cheaper than retro
I did buy my adaptors for Sega genesis from retro ( I had hoped it would work for Atari 2600 also) It works on Atari but when you push up on the Atari stick it also fires the button

It is also nice when you can find nothing to watch and fell like a game
turn on PC, pick what system, pick game and you are up and playing that fast, resting on you couch just like it was meant to play
with all that said . Any one have some old Turbo Grafix pads 4 sale?
darn things are hard to come buy and expencive on ebay