Most of the devices on the market, including the Phantom I mentioned, still weigh several kilograms. In addition, there are no safety features for those devices. For example, the device has only four motors. Drone motors are sort of like light bulbs: they can burn out very easily. Well, if you lose a motor, it's over, the device falls straight to the ground.
There have been many cases in which control of the devices was lost, which has resulted in many injuries all over the world. There was a case this fall in Beloeil, Quebec. There are still issues. The woman who was injured by the device had to be hospitalized and she is now suing the operator of the drone.
In addition, it is increasingly easy to fly drones. Less and less knowledge or attention is needed to fly those vehicles. They cost less, so people are taking more risks operating them. In the end, they take them out of the box, they push the power button, they start the motor and they fly the aircraft willy-nilly. They do not pay attention.
There are other risks, such as the batteries in these devices. The lithium polymer batteries are the same as the ones for the Galaxy Note 7 phones, which are now banned on planes, but they are bigger.