Answer: The dangers of a government that is "powerful" can come in many forms.
Explanation:
Think of it like this:
In the United States, politicians are at the will of people/serve the people, and if they do poorly, they get voted out. When a country moves into a dictatorship (See Myanmar) it is no longer about serving the people, but controlling them. It is a bit of a broad question because it really depends on who is controlling the government, so with that in mind the answer may be different. Corruption is another major issue in a place like Russia with an extremely powerful government, privacy rights etc, with a focus on enriching the elite of said country or keeping them in power.