The very reason why these things should never be allowed, is because the absolute protection of freedom of speech is ultimately the last safeguard against tyranny (before you get to violence anyway).
Why let the guy into my house with a gun and roll the dice on whether he intends to at some point do me harm? That's crazy. We've seen enough really malevolent politicians assume power all over the world and domestically, to know better than to take such chances. History is littered with endless examples, it's at best naive to think America can't suffer the same types of fate.
This is how revolutions are started. There's no "game over." A population always has the option to rise up against their brutal regime. Especially in a place like the United States, where individual freedoms are highly prized and there is a rather large contingent of heavily armed and often angry population.
I fear that if there is a violent revolution in a society as socioeconomically and ethnically diverse as the United States it would result in a civil war. I have no idea how that would play out in a country as developed as the United States but I don't think it would be pretty.
I wonder if this fits your bill:
https://en.wikipedia.org/wiki/COINTELPRO
And, from the little I know, the actual stifling part is [allegedly?] evident in malcom X and fred hampton cases, as well as others I might be missing.
http://news.cnet.com/8301-10784_3-9845595-7.html
Disclaimer: I don't actually mind as much as I should. I somewhat OK with a cyberpunk dystopia because the closer to Ghost in the Shell we get, the cooler.
Just because the U.S government has not yet used surveillance to stifle dissent, doesn't mean they will never do it.
Also, if in the meantime civil liberties such as privacy are sacrificed, when the time comes that they DO use surveillance to stifle dissent, it may be much too late to turn the tide, as dissent would then be required to stop their stifling of dissent.
It's also because it seemed as if Obama understood that there should be a delicate line between sacrificing liberty for security.
He also talks about people not wanting a 'big gov't...but a smarter gov't'.
But it is becoming increasingly clear that he was just talking smooth - but doing quite the opposite.
Please note, I am not an Obama hater. I supported him twice - I even have a Shepherd Fairy 'Change' poster.
But this is just disgusting man.
It's like someone that runs a campaign talking about how much they love guns, and how much they are going to protect gun ownership - then when they win, they talk a good talk, but then we find out that the government has been secretly buying up all the guns they can (to dry up supply) and closing down all the gun shops.
The fear of losing privacy to the government is based on the fear that this increased surveillance will be used by the government to smother dissent. This is a valid fear, but has the government yet used surveillance to smother dissent? If you can find a solid example of this, I'd like to see one (and for all I know, there could be many, I'm genuinely interested).
Until the government has been caught using surveillance to stifle dissent, it seems like increased surveillance only serves to reduce crime. Of course, there are illegal things that, in my opinion, should be legal, but this is a reason to petition the government for change, not break the law... perhaps a reduced ability to break pointless laws would galvanize the population into large-scale activism?
Fear of government surveillance is entirely fear of smothered dissent. We must make sure our fears of the latter are logically sound before we fear the former.
EDIT: Because I love arguing with myself, I'll point out that it's possible some wrongly illegal activities may be embarrassing for some individuals, and they would be hesitant to openly campaign for them. It still feels weird to argue for privacy on the grounds that people have a right to get away with certain things, hmm...
EDIT 2: 15 minutes and already COINTELPRO negated the argument. Good counter, thanks.
EDIT 3: Really appreciate that I seem to have gotten at least one upvote. I get really dismayed when politely-expressed unpopular opinions are downvoted, because I feel the best way to move the dialogue forward is to engage with opposing views, not hide them (even if your level of engagement is comprehensive refutation, that's still useful).