The Patriot Act allows government to listen in on private conversations without a warrant.
The requirement for a warrant is in the Constitution for a reason. Ignore it, and you open the door for government abuse of power.
Same for the power to lock people up without a trial. The right to a speedy trial is another safeguard to liberty, and so giving it up opens the door for more government abuse of power.
Depriving a citizen of life, liberty or property without due process of law is another potential abuse of government power.
Give the government enough power to abuse, and it is inevitable that it will be abused sooner or later to the detriment of liberty.
The real question is whether or not we value liberty enough to fight for it.