As humans, we have been given the free will to make our own choices. We are a very special creation; hence, the masters of our own will. We can make decisions and choose things irrespective of them being right or wrong. It is our free choice that allows us to respond to the attraction of prohibited things. At the same time, we have been given a conscience and a very advanced understanding of good or bad, positive or negative, and advantageous or disadvantageous worldly goods.
A basic tendency within us- urge- causes us to experience and know the things which are restricted. Normally, people feel enticed to do things we are told not to do. For instance, the use of narcotics. Every person is aware that their use is banned almost everywhere in the world and that they are harmful. Yet, millions across the globe are suffering from drug addiction. Even though some individuals get into the habit of drug use mainly out of frustration and depression, many enter this domain simply due to curiosity.
As a result, this kind of attractiveness towards forbidden entities can be dangerous and eventually lead to a miserable chain of events. The outcome of such desires always end up in drug-abuse; thus, it destroys mental and physical health, plays havoc with family and social life, and creates different sorts of troublesome situations. It is not allowed in any religious teaching or tradition either.
Basically from this case in point, it is coherent that any kind of desirability towards any prohibited commodity does not end well for anyone. Objects that are forbidden are forbidden for a rational and ethical reason.