As Engadget Japanese noted, this makes them convenient for travel because you simply need to find a local operator and then activate your internet choice plan. No need to exchange physical SIM cards or rent pocket WiFi devices. That said, the technology is fairly new and there is always a chance that the place where you are not having an operator. You can check the eSIM and Apple SIM coverage on the Cellular page of the company.
Apple seems to expand its support of the standard in recent years. The iPhone XS, the iPhone XS Max and the iPhone XR also work with the eSIM options, though they will need to be unlocked if you want to use two different operators.