Sometimes, a less rare card can be worth a lot if it's popular in competitive play, very old, or if not many were printed
While you don't need to win fast it is a lot easier to do so
Specifically, the creature you control with the lowest toughness as the first such ability resolves may not have the lowest toughness as the second such ability resolves
Even cards like WANTED: Seeker of the Sinful Spoils and Red-Eyes Dark Dragoon have been caught rising slowly over the past couple weeks, and hopefully we see a fresh reprint for these cards people are using for these engines
You can only have so many cards in your deck, though, so its important to include ways to make extra Goblins
They're releasing chronologically, and only the first seven have been revealed so far