Used at the right time, this can be a huge blow against an opponent who is strategically saving an action for maximum effect
Getting a better Sisays Ring but in most cases a worse Hedron Archive is fine
Sure, a Storm player without access to Past in Flames could just try and go off without it, or a Lands player could try to beat down with their Vampire Hexmages and Elvish Reclaimers alone, but its a much different threat compared to with those specific cards
The Color Black in Urzas Legacy: More of the Same old, same old plus some Anti-Tribal Cycling and echo were making inroads into the mainstream, but for Black the mainstream was still discard, reanimation and destruction
It reminds me of the choice players had to make with Attune with Aether where you need to get the right basic (Yes, I know the energy decks from Kaladesh were busted), especially in the 4C Energy deck