I've been a TT fan for years, remembering back when it was in FFVIII. This is probably going to turn into a long post, so just hold onto your seat and get ready for the ride.
The Current State of Triple Triad as a Whole
What's happened to TT in the last few months? Sure, we've had card additions and we've actually attempted a tournament system, but it's died down to just about nothing except a few who are still interested. Sure, it's a fun game to play at times, but only when you have enough cards to even make a 3* deck.
The current way they create those decks is to create balance in PvP by limiting what your deck consists of. This leads to obtaining cards to upgrade your deck. Once you reach a certain amount of cards, you become able to use 2* cards freely. However, this requires a bit of time and dedication to fight each NPC to obtain the card(s) that you need. The drop rate is also a tad abysmal at times, but through perseverance you can get all the cards.
Card Balance
The way that SE balanced the cards is very nicely done. However, there is a situation currently where exclusive cards only found in tournaments can't be found anywhere else. It makes the game a bit more unbalanced when it comes to this, as of current there have been win-traders frequenting the board for 140k MGP and the card. It makes the game a tad bland, and it turns down the incentive for a majority of the player base that used to be interested in TT(myself included) when it came out. Of course, there's no real way to fix this as SE has better things to look at. However, if there was a QoL thing I could improve, it'd be to create a bracket system based on how they do Lord of Verminion: RP. It'd allow things to run smoother and it'd bring people back to TT for actual competition. Creating a DF for the tournament as well can be a nice fix so that you don't meet the same person every time so they can win-trade over and over like people who are on top of the boards do nowadays with no skill.
The other issue is that these tournaments give out rare cards you can't find anywhere else. This can disrupt the card balance due to having a selection of 3* card deck compositions you can have compared to all the other players out there that don't have select tournament card. Unless it is given out by an NPC, this will remain rather unbalanced.
Drop Rate
Now I understand that everyone who is avid about Triple Triad wants all the cards. However, some cards only drop from dungeons and trials. This gives people more incentive to help those who are doing it for the first time for a card in exchange. Some of these cards are rather rare to obtain from a drop(i.e. Nidhogg), and require grinding the same place over and over. What would be a good change is to have the card there be obtained 100% of the time so that people who wish to enjoy TT with all the cards don't have to burnout because of the grind.
Is The Mini-Game Still Fun?
It indeed is. I really don't want to see Triple Triad be degraded down to Win-Trading where it's not even fun anymore, but it's been that way for months. If SE is willing to fix this for us so that our QoL with TT will return to normal like it was, then they'd see more people participating in TT tournaments. Otherwise, it just drives the whole player base away from the mini-game altogether. Lord of Verminion gave people the idea of an RTS, so I was glad it went into that genre at least and gave those people who are interested in RTSes something to do here in Gold Saucer.
Conclusion
If the tournament system isn't fixed, then TT will remain stagnant as it always has been. As for the card decks, there's some balance outside of the tournament win-traders that have access to more combinations. Leave your criticism and thoughts here as well if you like.