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.