I would argue it is to do with the medium. The feature length film needs a plot to sustain interest, for me and apparently at least a few other people. If it's

I would argue it is to do with the medium. The feature length film needs a plot to sustain interest, for me and apparently at least a few other people. If it's just a technology demo then it can be over and done with in 10 minutes - in Avatar they could have just started with the final battle. If Avatar were such a tech demo, then your comment would be unassailable, but as it is as a film is a bit lack-lustre.