Q) Why is there a problem implementing pegged assets?
A) The primary answer is that there can be no redeemability to the real asset on chain, for obvious reasons (since fiat/gold/silver/oil are not digital in the first place).
But bitcoin is on a chain and BItBTC is still illiquid , there is no reason anyone would hold bitbtc as its more expensive, less secure, not widely used, iliquid, subject to margin calls/ forced settlement
Q) Is there another design which doesn't have the same biased risk profile, or is this just a natural consequence of not having redeemability?
A) Discuss
Yes as someone else in this thread has already said other assets should be able to be held as collateral.
The Ultimate design in my opinion would be real bitcoin being locked into the bitshares blockchain as a sidechain and then this could be used for collateral instead of BTS.