I don't really see the point of a gold backed stablecoin.
The main problem with a backed anything is the centralised holding of the asset backing it. Since you're going to have to make your peace with that regardless of the asset you may as well stick with the dollar. If the point of a stablecoin is stability I'd rather erase the modest amount of volatility that something gold backed would produce.
I see no reason to pointlessly lose or gain a few per cent here and there. It would be an annoyance more than anything.
It's partly about the ability to easily hedge, trade and collateralize positions. If ounces of gold and barrels of oil were tokenized, they could be traded and collateralized just as easily as cryptocurrency is today instead of traders being limited to buying and selling exchange-issued futures contracts.
There may also be privacy benefits. Tokenization -- assuming the tokens are issued on a decentralized blockchain like Ethereum -- ensures the existence of secondary markets and the ability to avoid centralized exchanges and KYC. Regulations around stablecoins and cryptocurrencies (at least for now) are much more lax than those governing securities.
So, if you want to trade gold and do it away from prying eyes, this might be one avenue. It obviously doesn't solve the trust issue (it's essentially paper gold) but it brings other benefits.