When traveling abroad your don’t want to run out of cash - especially considering that some countries do not yet such a broad acceptance of credit cards. Same places also have restrictions with regards to ATMs. It might not only be difficult to find an ATM, but some ATMs are restricted to domestic use and don’t accept international banking or credit cards.
You can check the availability of ATM in the world on a website from Visa. Here you also are sure that the ATM accept international cards.