I don't think we should know ahead of time what runes we pull.
That isn't what I'm suggesting.
HOWEVER, how about once you've pulled a rune from the chest, you can pay the rune guy in the Refuge to identify a rune you already have on you for some exorbidant price...that way you know if you wanna replace what you already have ON, with the runes that you've pulled.
And if you have something that's half decent, you don't replace it with something that's complete trash.
Just a thought.
I think it's a good compromise.
On the one hand it doesn't allow us to knowingly trade runes, but at the same time doesn't ruin the decent armor we may already have on.