One handed pistol manipulation is a very important skill to have for self defense. The ability to fire an accurate shot and manipulate your gun with only one hand are another important part of your personal protection skill set.
Most people travel places and attend events with their family and friends. One hand may be needed to move family or friends out of harms way if something happens. You may also need to use one hand to protect yourself from a strike from an attacker.
It is possible you could be injured defending yourself or even have an accident prior to the event that limits your ability to use both hands. A criminal would see you as an easy target because of your injury.
One handed pistol manipulation is more than being able to shoot
The ability to load a pistol and rack the slide using one hand can save your life in certain situations. You may also need to be able to clear a malfunction.
The skills necessary to manipulate your gun with one hand and fire an accurate shot require training and regular practice. You should be able to manipulate your gun with your primary hand and support hand also.
Tactical pistol training should only be done with a qualified instructor who makes safety a priority. You can practice many of these skills using snap caps before trying the techniques with live ammo.