Umm, cause it's flat out wrong. Green is not "more iconic", its correct. It'd be like putting Jason in a football helmet, then saying "Why can't we give the new mask a chance." If Sideshow made a pink Superman, would you give that a chance too.
If Freddy had appeared in both green/red and black/red sweaters, then a debate about which is "more iconic" could happen. That's not the case. Black is wrong. Period. Sideshow wouldn't make such a blatant mistake, at least I would hope not.
But until we see the official pix, I wouldn't worry about it.
Or you can just not think and panic.
Chicken littles.