There is a focus on the character's personalities. They all have distinct personalities and relationship with one another. Interspersing this with card game jargon doesn't detract from this, and in fact, I think would be far better than divorcing card games and the people who play them.

Why wouldn't a person more interested in music than playing cards use a deck focused on musical instruments? Why wouldn't an ascetic wise beyond his years not use a deck with an aesthetic of hermit yokai (though I did consider giving him Shinobirds, I thought Yosenju made more sense with their play style and his personality). Why wouldn't a hotblooded rival with the need for speed use a deck where all its monsters rode motorcycles? Just because their decks are consistently the same attribute and because I mention the card's strategies doesn't mean I didn't put any effort into thinking up their personalities.

So maybe the reasoning is wind because wind. But it's also wind because of who these people are.