It would appear that the crew primarily enjoy the tactical elements of the game, especially bluff, counterbluff and confrontation.
Riker uses the game to hone his negotiation skills.
PICARD: Well, I'm the designated host. It would be a most awkward transition. You're the next likely choice. And Mister Mendoza will
certainly agree. He's quite impressed by your natural instincts.
RIKER: Excuse me, sir, but those weren't natural instincts. Those were poker instincts. A card game doesn't exactly prepare me for
PICARD: Yes, the stakes are higher. But then, isn't that when the game gets interesting, Commander?
TNG: The Price
Riker uses the game to interact with (and to assess) his junior officers.
SHELBY: I've only got two pair, Commander. But I've got to see that blind card. I'll call.
[She puts in her chips. Riker blinks... looks down at his card... turns
it over. It busts his straight flush. He's bluffing. Reactions. Wesley
groans, hangs his head.]
GEORDI: (delighted) You got him!
[Riker and Shelby's eyes meet. She collects the winnings.]
TNG: The Best of Both Worlds, Part I - Original Script
Data, in particular gets a lot from the game, learning about how humans interact in social situations
DATA: When I play poker with my shipmates, it often appears to be a useful forum for exploring the different facets of humanity. I was curious to see how three of history's greatest minds would interact in this setting. So far, it has proved most illuminating.
As well as helping him to assess aspects of humanity in relation to how humans calculate risk and exposure, which in turn has improved his tactical skills
DATA: In the game of poker, there is a moment when a player must decide if an opponent is being deceptive or actually holds a winning
hand. This decision is based not only on the odds, but also on an
appraisal of the man. Is he bluffing or does he have the cards?
TNG: Data's Day
Interestingly, on at least one occasion the ability to play poker proves advantageous when the crew is sent back in time with limited resources. Data's gambling skills allow him to earn sufficient money to build a scanner out of contemporary parts in TNG: Time's Arrow.