From what I see... seriously... just replacing the ink to black on white.... but we expected nothing more than that anyway...
As I see it, there's a breakdown to this that makes sense.
Gold Monarchs: pre-release, super-limited, not really intended to be released. Gold on black.
Monarchs: white on navy blue, because the the gold didn't pop on the blacks, considered a disappointment by T11. Also hyped like the second coming of Christ, Mohammed and Buddha all rolled into one - a big letdown to customers. But in the end, considered a solid deck, well-made.
White Monarchs: rare release, limited, looks great. Gold on white.
Silver Monarchs: unlimited (presumably the Monarchs are as well), and offer a perfect compliment to the Monarchs as a readily-available two-deck COMMON set.
Decks that don't come in commonly-available pairs don't sell to poker players. Magicians can use them for awesome color changes as well without having to risk damaging a rare collectible deck. Collectors, well - no one is twisting arms to get you to buy them, and they are an unlimited release. I want some, but I'm waiting for my paycheck next week. It's also great for people who liked the aesthetic of the White deck but couldn't afford it or missed out on buying it.