As always, it would be really awesome if nobody went to far with it. But of course, there are always people who step over the line of sportmanship. Take H2 for example, the rocket ship was turned into a erection 3 seconds after the game was released. Its amazing how mature people can be. I agree with people using Hayabusa too much, I prefer my Rogue helmet.
It would be cool if Bungie had a contest to find the most unique and awsome armor and that armor would become a downloadable content. Also mabye the runner ups helmets would become downloadable helmets in the same download package.
THIS IDEA WOULD BE GOOD IN TWO WAYS. One, is that people will like what they make obviously, and second, if you could post armor in you fileshare, NO FREAKIN HACKERS WOULD HACK FOR SOMEONE'S ARMOR! YES!!! EPIC WIN!!!
The only problem is you would need some kind of 3D image creator like 3DS Max, and not many people have that, let alone are good enough to make Spartans or Elites.
I dont think people should able to completly make their own suite of armour in some computer progam I think it would be cool if the gave you more parts like different visors higher arm parts lower arm parts stuff like that.
How about making your own emblem. It would be a lot simpler, and less time to download if it is put in a fileshare. When you make the emblem, it has a scanner that detects inappropriate shapes. I think that would be cool.