No doubt. iCloud, MobileMe, any service, can wipe your device by accident. Your data can also be accidentally destroyed by syncing with a "corrupt" device. Relying on Apple to preserve your data is waiting for a disaster.
The cloud makes syncing convenient, but it's not someplace to rely on for 100% data protection.
Now you could also backup to a cloud storage independent of Apple, where there is no sync involved. If you manually do it, it's in two places and having your data automatically deleted because it's not the "newest" version is not going to happen unless you make that mistake yourself. And in that case, nobody can help you anyway because you don't know what you are doing.
Not only that, but this world we are creating is too difficult for anyone over 60 to keep up with, yet they are being asked to, or forced to, by their banks, brokers, etc. They can't handle passwords well, so they use simple ones, write them down on their desk where people (nurses, housekeepers, children, whoever) can see them and exploit them, etc. It's a situation where security for those who can't handle the digital age has taken many steps backward.