If we're to fear any counter action they might do in retaliation then they win, they live to terrorize, they are terrorist, after all. They already hate Americans just for being Americans, living the way we do. What did we do to cause 9/11?
We didn't do anything to "cause" 9/11; that's pushing cause and effect well beyond any reasonable bounds. But Dizzy is right. They don't hate us because of our freedoms, or our way of life. To be sure, they hold both in contempt, but they would not have attacked us over either. Nor do they really hate us for our wealth.
What they do hate us for is our
power and our willingness to use that power to interfere in their countries, to support rulers that they oppose. Its really no secret what it was about, although there are lots of other political issues involved. But in the end, its because they felt that American power was being used against them and their interests. This is not to express sympathy with them. Although I agree in many cases those rulers were tyrants, Islamists did not have the answer either.
But as someone just pointed out, there are two sides. We are not pure good, and although they were very evil, they were not utterly without some claim to having been wronged. If we had not interfered in the Middle East, they would have left us alone. Again, I'm not saying this to blame America, just to point out that the motivations of the 9/11 terrorists were a lot more complex, and frankly made a lot more sense, than what you usually hear.