Cloud storage is a good concept if you know how to use it. It is designed for people on the go who needs access to work related files. Although it can be used for personal backup storage, the possiblity of someone having problems with it is greater that the possibility of your house getting burned down to the ground.
Well, with most cloud storage, it's a sync between your computer and the cloud. So, even if the cloud provider had a problem, you most likely do have the files.
As far as loss of data goes, sure a house fire is rare. Break-ins are rare, drive failures are rare, floods are rare...but they all happen. Far too many people never back up the data and just assume the power button press will boot up their computer every time. For these types, cloud storage is a saving grace because it's automatic.
I have a safety desposit box in the bank and I can keep hard drives in there if I want to. But I don't see the need why I should. But I would definitely not take a chance with the cloud.
I keep a copy of my important data off site. Things like scanned receipts, warranty information, digital pictures, etc. My wife would want to kill me if I lost all of our pictures, the pictures of the kids, etc. So, why not keep a hard drive or two somewhere else with recent copies of this important data. With robocopy, my sync jobs run in about 2 minutes. At most, I've lost a handful of pictures taken since the last backup. I just keep my offsite drives in my desk at work.