Air drops are a reliable way to get lots material on the ground fast, but it can also be pretty dangerous. The nature of regurgitating thousands of pounds on cargo in seconds can put the dropping aircraft momentarily at the limits of its envelope, and if things don't go as planned there is little time to react.
Then there is the issue of where the cargo ends up once it actually leaves the bowels of the drop aircraft, which is a whole other story. In other words, this is a demanding and risky business as you can see in the videos below: