"Maximising value is a backbone of Magic
Official explanation below: While many other cards reduce cost in a way similar to this card, this is the only card that can reduce cost without consuming any cards in the players hand or imposing any conditions, making it powerful in every stage of the game
If I have Azusa, Lost but Seeking and Oracle of Mul Daya in play, Id be able to play three additional lands a turn, two additional from Azusa and one more from the Oracle
If more people will be getting the promo, making it less valuable makes sense from a business perspective
Yet, with simple cards like Avian Oddity, you can put a Flying counter on Blue, letting every subsequent Dinosaur you play enter with Flying counters, too
You dont need to just play it in coin-flipping decks