Marvel Studios is officially becoming a legendary studio; much like features from Walt Disney Animation and Pixar, each movie release is becoming something of an event. The studio had the wise idea of introducing their own fanfare with Thor: The Dark World.
That said, I think the potential of one shots are being wasted with their exclusivity to home video releases. The ones we have gotten so far have been entertaining in their own right, yet exist mostly to flesh out a background character.
That said, wouldn't it be cool if Marvel played a ten minute one shot in front of their films in the cinema, and were used to flesh out the overall universe? The possibilities and their use in introducing new characters and concepts to the general audience are endless. S.H.I.E.L.D. Is called upon to investigate a possible traveller from another dimension, only to meet a cartoonish Howard the Duck. A Man Thing one shot. So on and so forth.
It would make the movie experience even more memorable, similar to the short films in front of Disney's animated features. It may or may not happen, but seeing Howard the Duck in front of Guardians of the Galaxy would be entertaining as hell.