Independent thinking is vitally important. If we all thought alike there would be no advancements in medicine or science or any other field. Everyone would be followers. Society would be boring. Innovation only comes from independent thinking, and innovation is the life blood of society. It is how we advance. If there were no independent thought, we'd still be living in the Dark ages. Neanderthals would never have evolved into intelligent beings. Life would stagnate.
We would be very easy to control if we were not allowed to think independently, so it is vital to introduce independent thinking in early childhood. It's the only way to develop and strengthen the mind.