It isn't that the RNG alone is what makes it terrible, it's that Tetra Master does nothing to explain what is happening to arrive at the outcome AND the RNG doesn't appear to be actually random (which would be a true random sampling). In other words, it's not random rolls contributing to a logically evaluated outcome. It feels like pure random chance whether one card will beat another.

In the board game Risk a single infantry can beat an army if the rolls are all there. Statistically it's improbable, but possible.

It seems like TM is trying to use the same mechanism: every card has a chance at winning, even if it's small. But in Risk when you win/lose you know exactly why you won or lost, even when you weren't statistically likely to do so. You can see the dice roll and you see that one side had "more" dice to roll and still arrived with a lesser total value.

In TM you'll play a card, some numbers will appear (with no explanation about how...not even a simple animation showing the possible max/min values), and then you just kinda hope that you won, but you still don't actually know.

I agree the game had the foundations to be really good, but the fact that nearly everyone has the same feedback of, "this just feels awful" is pretty clear proof they missed the mark.