These sexual instincts and desires have been created by Allah SWT and so suppressing them is not permissible, but rather the control of those instincts is what is necessary. The existence of instincts is necessary for the preservation, continuation and completion of the human race. If we did not have a stomach, we would die of hunger, if we did not have anger, we would not defend ourselves against danger, and if we did not have desires, the human race would be extinct.
Nevertheless, the satisfaction of those desires needs to be fulfilled in a correct manner.
Desires are like a gas cylinder in that if the release of gas is controlled, it can be used to heat and cook with, but if uncontrolled, can lead to an explosive and dangerous outcome.
Women have a desire to self-beautify themselves. If this desire is controlled and exhibited inside the home, a sweet and cherished life full of love will result however if exhibited in the streets, results in the breakdown of family units in the community. A man who sees hundreds of beautified women on the streets and then returns home will pay little attention to his wife because his relationship with his wife becomes diminished.
In addition, those who are unmarried will (as a result of the above) have their desires provoked and a like a water candle that you carve out and burn, the thoughts of the unmarried will transgress boundaries and be destined towards wrong, resulting in a path to be followed leading to running away from their homes, threats, suicides, sexual assaults and mental illnesses.