Crossfitters have something of a controversial approach to form and technique that is still heavily debated among different weight lifting disciplines.
There’s no doubt that crossfitters are some of the most athletic and highly skilled athletes. This may justify why dropping the weights has caught on. People who are lifting more than their own body weight or even more than that simply have no alternative but to drop the weight as lowering can have serious safety concerns.
It's simply too difficult to control very heavy weights beyond a certain point, and even though it’s possible to lift them up, lowering them can be simply too difficult.
There is also an element of people enjoying dropping weights, however, which may be a less valid reason why this has caught on among athletes who don’t really need to drop the weight.
Some people enjoy the spectacle that dropping weights can cause. There’s almost always a deafening crash as the weights clatter to the ground, the sound of metal rattling and floorboards thudding is enough to blast through even the biggest of workout headphones.
This attention grab is certainly an aspect of dropping weight that some people find distasteful, especially when it’s done dangerously.