It is definitely difficult to rip out a cannula. And, if you think you are more clumsy than most, you can tape down the tubing to reduce the risk.
I don't know about "randomly" ripping out a cannula. The worst case I can imagine is the glue loosening in the hot weather. But I have heard more examples of this happening with a OmniPod. Remember, the OmniPod still has a cannula it is just not on the end of a tube.
One of the reasons I avoid putting my patch pump on my arm is because I am more likely to knock it there but it is a common place for many.