Speech made our country great. We started out as a series of letters, articles, and speeches.
Speech made our country progress. The melting pot allowed people to challenge cultural expectations, and speech drove people to act.
The infringement of speech made our country sterile. Limitations on comfortable and acceptable and, worse still, correct took away our dialog. People became sensitive because they were told they should be. People stopped saying things... not because they didn't believe them, but because they shouldn't say them. We sealed our differences and problems away behind a facade of correctness.
The infringement of speech has broken logic and sense. Now that it is wrong to say a thing, it becomes wrong to think the thing. Our limitation of speech has turned into a limitation of thought.
I may not agree with what you think. I may not agree with what you say. I may think your opinion is bad, or wrong, or even dangerous. But it is yours to have.
If I stand by and deny you have a different opinion, I am enabling the perpetuation of your opinion by my inaction. It is only through communication that we can learn. Without dialog, we are stagnant.