This question comes up again and again. I am constantly amazed that in the 21st century, in a supposedly enlightened civilization, there are still people who think it's a good idea to force a left-handed child to switch to the right hand.
I've been operating the Left-Handed Page for many years and have heard from thousands of people, left-handers of all kinds, as well as researchers, writers, teachers and parents.
I have never come across any subject of forced switching who claims to be glad he was switched. Most describe it as misguided at best, and as vicious child abuse at worst. Many excuse and forgive their parents for having forced them, because they see that the parents were either well-meaning or simply ignorant. But that does not make the victim feel any better about the experience and its aftermath. While a small minority seems able to switch without difficulty, this is not typical. Again and again, I hear from people who say that having been forced to switch caused problems that bothered them for the rest of their lives. Physical awkwardness is a recurring problem, preventing the person from doing well at sports, interfering with the ability to use tools, contributing to bad handwriting, and causing the person to be tense and easily fatigued. Some report mild to moderate learning disabilities, difficulty thinking, social problems, emotional isolation, etc. Surely a loving parent would not want this for his child.