This is good, but I think a more effective way is to bring up some hypotheticals. You don't even have to make up your own. Just look at history and you will find lots of examples of how secrecy leads to corruption, in-fighting, negative psychological effects, loss of free expressions, fear, oppression, etc.

One neat way to approach this would be to talk about an example that happened in the past and draw parallels with what it going on today. It's difficult for people to understand or see where all this leads, which is why there's so little revolt. Unfortunately, by the time people feel the effects it's too late.