Remember when Rush Limbaugh was blamed for the Oklahoma City bombing? Remember when the term "patriot" was used by the left as a slur akin to "potential terrorist"?
This is a far more complicated issue than it may seem. A change in the political wind could put a lot of polifical dissenters of all stripes on the watch list.
Do you trust the government to do this? What is the government changes to a new regime you don't like. What then?