Lots of climbers hate rappelling, but sport rappelling has been around for quite some time, even while others refuse to acknowledge that people get enjoyment out of such activities. Regardless, I imagine that a Diamond rappel would be far beyond the scope of "sport rappelling". It is a tough mountaineering route, and for all of the reasons that were already mentioned, I imagine that the skill required to go down it would be about as involved as the skill required to go up it.
On the other hand, I haven't climbed or rappelled the diamond, so I'm really just guesstimating here. JDip, I see no harm in asking the question that you did, and I am laughing a bit at a lot of the self-righteous and insulting responses. Suffice it to say, the overwhelming majority of people seem to think this is a bad idea, but I don't think that really gives them license to ridicule you for asking about it.