While prices have been steadily increasing in the five years since its release, the secondary market for Celebrations is now exploding again, with some products seeing prices increase by as much as 64.75 percent, according to Collectr
And while the new commanders that care about this stuff are overwhelmingly Golgari, with the exception of the unplayably-mean Winter, Misanthropic GuideWinter, Misanthropic Guide, there are still some older commanders that care about card types that are other colors
Two copies is excellent for powerhouse cards, the creatures and spells that cost a lot and have a significant effect on the game, but arent necessary for you to win if your primary plan of attack works
Being able to pay three mana to cast anything from the graveyard for a turn essentially translates to drawing a huge number of cards at a very low cost, but without the randomness that comes with actually drawing the cards
(1) Your Toon monsters can attack directly
They replaced the older Draft Booster and Set Booster split, giving players one main booster type that works for opening, collecting, Sealed, and Draft