It is true that parents shoulder a huge responsibility and that raising children is by no means an easy task. However, I completely disagree with the idea that we should therefore force all mothers and fathers to attend parenting courses.
In my opinion, the idea that all future parents should take a parenthood preparation course is completely impractical. Many prospective parents have jobs and busy schedules, and they may not be willing or able to attend regular parenting classes. This raises the question of whether those who missed the classes, or perhaps refused to attend, would be punished. I believe that it would be wrong to do this, and it would therefore be impossible to enforce the idea of compulsory training for parents. Besides, even if parents could be forced to attend, I doubt that people would agree on what good parenting entails, and so it would be difficult to create a parenting course to suit everyone.
As well as being impractical, I would argue that training courses for parents are unnecessary. Mothers and fathers have been raising children without any formal help or official interference for thousands of years. Parenting skills are learnt from family members, friends, neighbours and the surrounding culture. Perhaps more importantly, adults learn to be good parents by instinct, by trial and error, and by getting to know their own children; for example, a good parent will try different strategies when faced with a badly-behaved child, and will gradually develop an understanding of what works to correct the behaviour. None of this requires the intervention of a taught course.
In conclusion, while compulsory parenting lessons might seem like a good idea, I believe that such a scheme would be unworkable and largely pointless.