If I may add my two cents: I think there should kind of be both. Recreate the original game (SMB) exactly as it was as close as possible. Then keeping in mind that a good player on the average could easily beat the game between 7 to 10 minutes if they so desired. Add in the fact that with a newer engine and controls that time might even be cut slightly shorter. Keeping this in mind, I would welcome a strict recreation, but then at the same time would enjoy an enhanced version, that borrows elements from the original (level designs being about the only thing you can borrow), but includes new elements like perhaps multiplayer or expanding levels to make benefit of all the new objects found within the game that is NSMBW.
I understand that the team behind this hack's goal may be a strict recreation, but with what I and others have said, I'm not sure that such a hack will offer substance and replay value. Sure it's great for the sake of what it is, but after playing it twice (once where you go through every level and once where you take all the shortcuts), I couldn't imagine playing it too many other times except when wanting to show it off to friends, especially since the original game was largely a single player game and the NSMBW is more geared towards the multiplayer aspects, which this recreation would make little use of, I would imagine. Speaking of multiplayer, unless this hack comes up with a way to remove the ability that is multiplayer then you would be essentially allowing a game that is, by today's standards, easy to become even easier.
Either way though I intend not to sound harsh or critical of the genius that is behind this project in fact I applaud it for the brilliant and immense effort.Whatever becomes of the final product / release I definitely look forward to it.