This is an important question. The most important reason for disposing hazardous waste is to protect people. There are many hazardous byproducts that come from society that needs to be taken care of, if we are going to live healthy lives. Another reason why we need to dispose of hazardous waste is to protect the things that we need to live, such as water, food, livestock, air and the like. In a short, the goal here is to preserve life through the proper treatment of hazardous wastes.
In terms of the cons, there are two main ones. First, if this hazardous waste is not disposed of properly, then it can be disastrous, after all it is hazardous! It can impact and destroy life or nature. Second, often times to dispose of hazardous waste, there is the process of transportation. This can be a con due to the inherent risks involved in transportation but also due to the fact of additional costs.