Firstly, everyone with the Wii U version still has it and you can play 4 player without the easy characters. Secondly, how often to people play four player? It's possible some people play this mode all the time, but even so if I did I wouldn't mind playing as Toadette. If you play 4 player all the time, again, you still have the original game.
It's also possible Nintendo might patch in four player with blue toad.
All that said, New Super Mario Bros Wii U Deluxe looks great from the reviews I've read (including the Digital Foundry video review above) and the addition of Toadette and Nabbit makes the game more accessible to people that might not mind playing with you but would get frustrated dying a lot if they aren't hardcore gamers. For instance I could see my young son playing as Nabbit as he gets better over time and can play as the more traditional characters.
