It is not necessarily "wrong" to do something like this. There are many examples of a bunch of composers working with someone else's material, perhaps most famously when Anton Diabelli sent his little waltz to many famous composers and asked each of them to write a variation. Obviously seeing this as a weak idea, Beethoven instead wrote his own series of the thirty-three which were to become one of his masterpieces. These Messiah "remixes" are grim. Perhaps the main problem, apart from the obviously facile, throw-away quality they have, is that none of these composers seems to have considered why Handel composed his work, what it meant to him, or what his impulse was. They are only working with the musical elements (the notes, rhythms, harmonies, etc.) and completely ignoring the soul of this masterpiece. These are merely doodlings by a group of technically expert but musically bankrupt contemporary composers. I defy you to listen to any of these pieces more than once and honestly maintain that you get more out of them on subsequent listenings. The only time they grab you is when a snippet of Handel's great music is allowed to emerge on its own for a few seconds. You then realize what a huge waste of time (well, probably not all that huge, actually) this project was.