WA, you're kind of missing the point. It's not that you don't know what you're doing with a hidden setup, it's that no one does because it's a completely different game driven by luck. Why don't we just bet on a random number generator?

Understand--a player can look for tells, but he can't know what to do about it unless he knows the game. If you could tell your opponent's cards in a poker game with 100% accuracy, what good would it do if you don't know which poker hands are winners? Half-blind setups broaden the range of possibilities and eliminate the universal dominant strategy (namely, all players play the same regardless of role and alignment) without determining the outcome with what is effectively a dice roll. Back to the poker analogy... You can play blind man's bluff, but you can't play blind man's bluff with random hand values.