[S]tablecoins represent a simpler product to audit [versus banks]. However, these organizations (i.e., exchanges) are very complex. TUSD (i.e., trust company and development/issuer company are separate) is likely a safer approach than the exchange company and development/issuer company being combined.
The only advantage that Tether, XRP, or TrueUSD offer is regulatory arbitrage, which is temporary in nature. Eventually all the rules that make it annoying for banks to use USD for settling cross-border payments will apply to XRP and Tether (and TrueUSD) as well.
My view is that the centralized collateral approaches (TrueUSD and Digix being the two most well-known) are not socially scalable enough to be liquid on a global scale in the long run, but they could serve certain customer bases and also be good collateral for more decentralized approaches.