This means that, while your opponents will struggle to keep up with your tempo, you can build up your resources and control the state of the board more efficiently than ever
Take control of target artifact or enchantment
While Sram, Senior Edificer is also good draw, its only off of cast, and so should always be second choice to Puresteel
Another intriguing aspect is the possibility of treating colorless as a supporting subtheme for mono-colored decks
Furthermore, Vedalken Engineer can actually tap for two mana of any one color that can be used on artifacts or artifact abilities
While the Mana Vault isn't a perfect substitute for any of them, it has a similar role in a first-turn hand to Jeweled Lotus and Mana Crypt, and players are presumably placing bids to grab replacements