I think some people avoid doing one-handed shooting simply because they don't think they'll be any good at it. And we all hate to do things that don't make us look good. But, training is about developing skills that need the work, not just showing off what we do well. The fact is, one-handed shooting isn't as tough as some people seem to think, if it is done correctly. The fundamentals of a strong stance, firm grip and good trigger control are not just a good idea; they are essential with only one hand controlling the gun. With a little practice, you can be shooting accurately at distances that far exceed the usual three yards on qualification courses. And be shooting well while moving. And making a smooth transition to shooting well with your weak hand. Try it. Amaze yourself and your friends. Befuddle and intimidate your enemies. In other words, look good. Whatever your motivation, do it. It's your life.
Just how important is it to practice with your non-dominant hand? A few years ago there was a raging debate on one of the internet gun forums. It was about the importance of one-handed shooting in general. Several folks were quite adamant that practicing one handed was just a waste of time, as there rarely is a need for it. As if in answer to such ignorance, a couple of weeks later there was a police shooting in a small community near where I used to live. The lone officer on duty in the town was dispatched to a domestic disturbance at a residence. Since he was alone, his backup was coming from an adjacent jurisdiction. When the officer arrived at the front door, he was standing on an "L" shaped porch that ran on two sides of the house. As he was knocking on the front door, the suspect (they call them "actors" in that state), who had left the house by a side door onto the same porch, suddenly came around the corner of the house, gun in hand. He fired just as the officer was drawing his pistol. The shot hit the officer in his gun hand, causing him to drop the gun onto the porch. At the same moment, before he could fire again, the shooter's attention was diverted by the arriving backup officer. In that instant, the first officer was able to reach down, retrieve his gun with his "weak" hand, and forthwith dispatch said "actor" to his next life. It happens! It is sheer folly to imagine that it will not, or that it does not. I can't remember who said this, and I may be paraphrasing very poorly, but it does fit the situation: "Reality has a way of making a fool out of denial." Don't just train for the best of circumstances. Train for the worst. And please, stay safe out there.