There are many reasons why smart people don’t blindly store all their files on SkyDrive (OneDrive), Google Drive or similar services. Most of them should be obvious, especially the security related reasons, so I won’t repeat those.
Another less infamous reason is something like this:
Now, imagine you completely rely on your being your data as safe as possible in the cloud and then you are just getting hit in the head with this policy. Sure, if you store important data, you probably access it frequently, etc. However, I already met people, including myself, who suffered from premature file deletion, either because the retention period was extremely short or the data was important enough to be backed up, but not urgent enough to be accessed frequently. Sometimes I need something saved that I want to access in 2 or 3 years from now. Well, now Google doesn’t allow you to do that, anymore.
Never trust a big company.
If you want safety, look at these solutions, I personally use in my life (you probably already know most of them):