If the planners of cap and trade could not foresee this - what can they see at all? One wonders not.
The object of cap and trade is to provide a market for those people to play in. You know, the same people who recently brought us all such a triumph in mortgage trading. At least a mortgage is backed by something, you only lose part of the value if it flops. Carbon credits are more like, say, tulips. They have no intrinsic value. If (when) the market flops, and you're stuck with the right to burn carbon in a world where nobody pays any attention to their right to burn but burns anyway, you can't turn that position into anything of value.
The trader people have managed to convince government the world over that CaT is better than tax. They may be right, but in their eyes the important thing is nobody gets to dip their beak in a plain tax.
No, don't think for a minute that I favour a tax, I am a denier.