Some information the public has the right to know while other information is better to be withheld.
There are plenty of reasons why it is better not revealing information. Withholding information that may put the population in danger would be better than revealing information which would bring chaos.
On the flipside, transparency and honesty between the government and the public are very important. Transparency is essential in order for a democracy to function and honesty is important in cases when there is need for strong relations to be created. And although I support the idea of freedom of information, the general public will never be educated enough to maintain consensus and national problems. In these cases withholding information helps to ensure stability in terms of national security, preserving the peace and well-being.
The main reason authority keeps information is the fear from criticism and disapproval. A rational society would never be satisfied with vague information and would want to take part in the decision-making process. Government has a lot of information which the people may have an interest in but still some of this information is dangerous. Things like war strategies and secret missions need to be withheld.
Being kept in the dark on some things as long as it's truly for the good of the nation and not for someone’s benefit is acceptable. For example if government find the cure for cancer but decide that it would ruin pharmaceutical companies and chose not to reveal this information it isn’t right. On the other hand, there is a lot of information which public doesn’t deserve access to. Like information that endangers the government.
Another reason for withholding information could be to cover mistakes and not causing discontent. The government always makes big promises and eventually it will have to fulfill some