Right, but they're secure enough for most people. Think about it, the chances that someone gets access to my own computer (stealing it, breaking into my home, or hacking it over the Internet) are higher than the chances of that happening to a professional service provider. At least that's the case for most computer users. I heard recently that 25% of all computers in the world are zombified. So much for security on your own computer.
But anyway, that's why I said if you can improve on their offering then go for it. Given the current options, they're the best that I know of; and I say that knowing that they have a lot to improve. So, if you build a better service, I'd consider switching.
I think it's a good idea, but already done, though. I use Carbonite to keep an online remote backup of my hard drive. They charge a fixed rate regardless of the capacity of the drive. Of course there is always space for competition, so if you think you can improve on their offering, then go for it.
But anyway, that's why I said if you can improve on their offering then go for it. Given the current options, they're the best that I know of; and I say that knowing that they have a lot to improve. So, if you build a better service, I'd consider switching.