How to Train Your Dragon isn’t some interpolation of the 2010 animated film, as it’s more or less a carbon copy, with the filmmakers having recreated 99% of the original in live action. And as Gus Van Sant proved pretty decisively back in 1998 with his remake of Alfred Hitchcock’s Psycho, the only value in such an exercise is the degree to which you’re curious, if at all, about its fundamental reason for being.