one thing that some people has mentioned is the fact that Select and Start do different things.
sure, back in the day of NES that was the only way to select 2 players on games like Super Mario Bros.
but now games like Borderlands 2 uses Start to display the pause menu that is used to invite friends online and change options, and Select to display the inventory, map, missions, skills and all that. how you are supposed to do that with just one menu dedicated button???
games like Zelda Twilight Princess had to be inventive and use the D-Pad for the map and inventory, but in my example above, the D-Pad is used to change weapons too.
another example I have is from Metal Gear Solid Twin Snakes, where you need to press Start + A or B to open the pause menu or codec, FUCKING START AND A OR B. that's what happen when you run out of buttons, you need to start making ridiculous combos to make the game working. how are you going to use the codec on Metal Gear Solid 5 on PS4, Options and X???? that's not even possible grabbing the controller the way is supposed to.