Because while, yes, black decks are generally very good at making this sort of payment and, yes, creature tokens are not at all difficult to come by, the additional cost here is not optional
It gets a +1/+1 counter on it whenever you cast a creature spell, and then makes each creature spell you have cost one mana less to cast for each +1/+1 counter on it
Umbreon ex at 960.96 and Sylveon ex at 238.74 mean even the sets second-most-expensive card would rank in the top ten across all other sets
As a mono-white creature, Gandalf the White can easily fit into any deck with white mana, making it even more flexible
There's plenty else to be excited about with the upcoming set, including the possibility of adding real-world historical figures like Sokrates, Leonardo da Vinci, and Cleopatra into your deck
Collector exception : cards valued for art (SARs, full arts) recover faster than playability-driven cards