First, I think they want to provide an alternative to the dominant but controversial Tether. This will help bring confidence to the stability of counterparties that hold stablecoin throughout the global ecosystem of cryptocurrencies.

Second, I think they want to expand their listed assets slowly but bringing a stablecoin will permit them to attract crypto into their wallets instead of fiat. Most investors were using coinbase to buy into BTC only to transfer to the likes of Binance for access to other coins. Now, as they expand their assets listing, they want to attract crypto to their wallets and a good and liquid stablecoin could help.

Lastly, I think they want to leverage the technology of quick settlement instead of the traditional fiat banking system that is slower and more expensive.