Without independent thought, nothing would ever change! 30 years ago someone said, wouldn't it be neat if people could carry their phones around with them all the time? Most of the world thought this was pure science fiction, but look at us now. The independent thought and the engineers have brought us phones that do everything. What was once a James Bond-like gadget, is now reality.
Independent thought made the the Colonies revolt against the British Empire to declare themselves the United States of America. No where in the world had this kind of democracy ever existed, but we tried it here, and the world took note. It wasn't long before other countries such as France, tried their own experiments in democracy which came from their own independent thought.
If you are not able to think independently, then you are just a tool for other people. A person who cannot think for him or herself will just do whatever some other person tells them to do. This is no way to live.
In addition, a person who cannot think independently cannot really hold a good job. A person who has to be told what to do at each moment, or who can only be given very simple tasks to do repetitively, will not be able to hold a job that pays well.