I agree with you that many blockchain games are boring and not worth playing. First-generation games like Cryptokitties are especially bad because you have to pay gas costs for every transaction.
And I am not a fan of Relentless. I played it, and it was OK. But it's not really up to par with what I expect from a CCG. It's just too simple.
But I've played other ones that are really fun, like Forgotten Artifacts and Gods Unchained.
And you can't really separate the blockchain aspects of these games from the games themselves. In Forgotten Artifacts, for example, the main reason the game is fun is because you might loot some collectible item out of a chest if you make it far enough into the dungeon. In Gods Unchained, you can trade the cards that you collect - just like you would with a paper CCG. This is completely unlike MTG: Arena and Hearthstone, which prevent you from trading and therefore prevent you from building a deck out of singles.
These games are also run on centralized servers. The only time a player has to pay gas fees is when he transfers an item to his wallet. So these games are much cheaper to play than Cryptokitties, Etheremon, and other first-generation blockchain games.
My point is that you can't judge them all alike. Most of them are junk. I agree. But there are some gems in the blockchain game niche as well.