Players need new cards to keep up with the game, of course, but that doesnt account for the huge success of Collector Boosters
It doesnt have complex mechanics, confusing interactions, or clever tricks
In other words, we get 3-4 mana worth of value each time we cast a noncreature spell large enough to draw two cards (not to mention Hero tokens)
however, cards like Elsa - Snow Queen and Elsa - Queen Regent count as different cards, so players can have up to four of each of Elsa's various cards
It isnt excessively dominated by bombs or 5c piles (though the set does support both), so youre very much trying to draft a cohesive deck
In Final Fantasy VII, your weapons are a huge factor in the materia you can use, and Equipment is the Magic equivalent, hence why the deck was built around it