Regarding about the bet archive.. Its no use if we can't verify them as probably fair.
Well, I think the same, but as I said, it is the first version of the feature, and it covers the needs of the majority of players.
Anyway, because of what @adaseb said, it is always better to check the provably fairness while you are playing.
Just like what i said earlier Sir, there are times probably fair verifier is not working..