Like we've said in the past: it is still a company, and what does a company do? It analyses consumers' demand and preferences...then it comes up with an ideal offering to maximize the sales, right?
It could also be argued that they did the same thing for other models such as the Scar and Eye Jacket 3.0, both of which sold horribly at retail and were quickly discontinued. X-Metal is supposed to be the best of the best... a warm grey lens simply does not represent that, that's all I'm saying. And you are correct: crazy colors aren't always necessary. But black or slate iridium would have been far preferrable to just "grey", and would have also done the job nicely.