Simply because a card can be used in multiple decks does not warrant a cost increase. Unless those decks are more potent when combined, there's no reason to up the cost.
Maybe you feel like making a deck out of all crystal and cat cards and buffing this card to the moon? Well, looking at all the cards you made, none of them have any excessive buffs, and I don't think 1 attack is worth 2
higher than Horned Frog while having lower stats.