It is not often that attempts have been made to compare storage services in the cloud with external storage devices. And the vast majority, have tried to put both on the same level, when they are not at all comparable, or at least from my point of view.
A few years ago, when our connections were not too fast, in the days in which we should be constantly worrying to control the use of the network to prevent our downloads will slow down, then yes we had a direct dependence on external storage. And it was unthinkable to be depending on a server to be able to access our private files.
ICloud, and cloud storage services in general are really useful?
Now, the tables have changed. Our connections are able to perform file downloads and uploads fast enough to not notice the exchange. The world begins to accept the comfort, to be able to access your files in any place, without needing to load with a specific device.
In the case of iCloud , we are talking about a fairly closed service as compatible devices with the same, and the ways we have to use it. We are not talking about a Dropbox, but something more limited. But it's the same principle, finally, after all , a service able to keep our documents "saved our lives", ie, they are not exposed to damage our devices can suffer. They will not disappear if our mobile suddenly crashes.
And that's where we find the true beauty of these services.
Security and availability, two elements with certain problems to solve
On the other hand, with the recent attacks on various services, it is called into question the safety of these "clouds", and that this is one of the major drawbacks that our files are in outside servers. We can not personally handle your security beyond activating 2-step verification. Neither can access if we find no internet, or if these servers fail. And that's where the external storage comes on the scene.
I personally believe that, at present, flash drives, SD cards have become a resource storage for sensitive data. That which we do not want to escape from our control, which we may need at any time, even without connection. As I said at the outset, these are no longer comparable storage systems. They are complementary.