A standard deck of cards is the most versatile item in your gaming collection. The number of possible games is in the thousands, from Patience to Poker, from Bridge to Cribbage.
This popularity has come around for many reasons, and I’m going to look at a few of them.
A deck of cards is a small, portable object, which is a large factor in its favour. It is easy to take a deck of cards anywhere, and to play a game within a very small space.
Card games can very easily have both random and secret elements, achieved by shuffling the deck and dealing out hands of cards. You can choose to limit these elements to any degree, by playing with face up cards, or sorting the deck.
A deck has many symmetries with it. There are four suits, in two colours, each suit has the same thirteen cards. This makes it simple to create games with the aims of collecting various types of card (same suit, colour, card value).
It would be an interesting exercise to create new card games using standard decks of cards. It is difficult to immediately think of games that would not simply be variations on existing themes, but with enough effort it should be possible.
You are working within a well defined set of constraints when designing for a deck of cards, and the required discipline should translate well into designing other games, as any propensity to designing your way out of trouble with extra cards should be removed when you have experience working within such limited means.