For me, it really taps into the terrible misfortune caused by those who think they are smart enough to attempt to enforce how other people should live/behave.
> The conscious and intelligent manipulation of the organized habits and opinions of the masses is an important element in democratic society. Those who manipulate this unseen mechanism of society constitute an invisible government which is the true ruling power of our country.
This attitude is what makes me wary of the current top-down attempts to rein in misinformation on the web. There is a visible assumption that people are not to be trusted and must be lead somewhere. If necessary, by a bit of force. (Deletions, bans.)
Trading misinformation for a nanny-knows-best authority that manipulates you into its preferred position is not much of a trade at all. Either we accept diversity of humanity (including morons), or we will edge our societies towards benevolent informational autocracy that won't stay benevolent forever. I strongly prefer the former, dealing with morons, even though it is not pleasant.
I also think that more and more, I disagree with the book's outlook that people are more or less like putty and can be bent into doing anything you want - I've come to see people as strong in their fundamental convictions yet open to things they don't have any fundamental disagreements with. And more than willing to let you guide them in the direction of things they already wanted. Sort of an Adam Curtis outlook I guess.
Whether that makes propaganda of any given form justifiable is another matter.