With tons of sub-par camera videos that are hanging around on the internet, and write-ups that are probably inspiring fans to watch said videos, people are already going to watch the Avengers: Infinity War trailer.
So why not release the footage in the highest quality for all to see?
Those problems complement each other, as they link into one gigantic whole.
Marvel Studios should be doing the same thing they did when the Avengers: Age of Ultron trailer leaked to the internet: they should release the hi-def version, so they can stop the pirated spread of their material.