Why Gwent is not popular? I can't speak for everyone but I'd like elaborate why the game cannot be popular with me.
I left the game after the launch of HC for a period of 10 months. A few days ago, a huge nostalgia hit me and for the first time in a long while, I logged into my GOG account and fired up Gwent. It was a pleasant surprise to see a new faction with the option to have Dijkstra as a leader. I always loved Dijkstra both from the Witcher games and Gwent Beta. That 4 power spy gold card was a go-to card in every single of my NR decks. Profit + fee combo seemed interesting and instantly built a DJ's syndicate deck. I mean I copied and pasted it from a meta snapshot I found online.
The more I played, the more I realized why I left in the first place. No matter what I played (whether it was a Meve midrange, Ardal tactic removals, DJ's profit/fee,) no matter how complicated a card ability was worded, no matter it was a gold or bronze, essentially I was setting them up to do +2 boost or -2 damage. Yes there were different cards doing a little different than other cards but it seems like they didn't escape much from the concept of +2 boost or -2 damage.
Going in a little technical, one other thing that discouraged is the hand limit. It just didn't seem right that a player wins round 1 with 2 cards down and still be able to start round 3 with an equal full hand. That just makes having rounds complete pointless. And as usual, playing second (not getting the blue coin) is still much better. Also having provision costs makes me feel like doing tedious algebra and takes away the joy of deck building around an archetype.
That being said, I do admit the current state of Gwent is much better than when it was launched Oct. last year, but it has lost that adictiveness it once had when it was in beta. I couldn't play more than 3 matches in one sitting after gaining sufficient knowledge to pilot a deck. Cards lack diversity. Different wordings but essentially the same ability.
To add my 2 cents on why the game isn't popular right now ... well in my opinion, currently, there are 2 huge online card games in the market, MTG arena and Hearthstone. MTGA is still in beta and has been growing substantially. I never played Hearthstone so can't say much about that game but MTGA doesn't lack diverse and fun cards. It is a draw dependent game but draw RNG is the only RNG the game has. I do get tired of MTGA by playing it daily something I have never experienced with Gwent beta but to me MTGA is the game that I am able to play more than 3 matches in one sitting.
I don't wanna divulge in too much of "my gwent beta" drama, but I just wanna say that I spent 400 dollars to support the game I loved more than any game and wanted to support and appreciate CDPR for making my favorite game in the world. It was a sad day to see it go and the news of Gwent isn't doing well right now doesn't make me happy either. I was genuinely shocked to see, at rank 25 on the leaderboard, I was placed at 45k. "I am sadness" describes perfectly on how I am feeling about the whole scenario.
I am ready to take another 10 months break. Perhaps a hit of nostalgia will come early this time around or perhaps it won't come at all. Until then, best of luck to everyone.