It's not an issue with it being bad to store data in the cloud, it is the fact that some people used it as the primary and ONLY source of the data - if you used it as a backup for data that already exists on your desktop then its not such a big deal
Skydrive stores my files in the cloud, as a copy of files I have stored in a Skydrive folder on any machine I happen to have it installed on, so if the cloud fails or in this case, erased, I still hve the files
If you have stored anything in a cloud only format and no personal backup, either on a USB HDD or a local PC, I have no sympathy for you because you are terminally naive and/or stupid