I don't have a problem necessarily when people use the word 'magic', but it's when you try and press that person to be more specific and they can't explain that gets my gears grindin.
It's pretty easy for me to describe why a game would be 'magical'. It's when almost every aspect of the game is cohesive and matches up properly, level design, music, graphics, etc. If NSMB had better graphics and music, I think it would definitely be comparable to SMB3 and World for me. Of course, I'm one of the few that didn't mind the level design in NSMB.
For NSMB: Wii, it appears they've fixed those issues (graphics might still be of the same style, but it looks a helluva lot cleaner), and I trust Nintendo for the most part to deliver with the level design. So this game should rock.