The short reason is, because the principles of '98 may be our only avenue of escape from the ever encroaching federal government; by providing a way for the states and their residents to nullify any federal law that they disagree with.
Want to know more? I recommend The Politically Incorrect Guide to American History by Thomas E. Woods, Jr. I found the audio over at Mises.org, but it seems to have rolled off. It's as good a place as any to start, and it's pretty entertaining if you are into history.
The Principles of '98 are expressed in the Kentucky and Virginia Resolutions
which were drawn up and passed in direct opposition to the Alien and Sedition acts. Quoting the Wiki article:
The resolutions declared that the Constitution was a "compact." That is, it was an agreement among the states. The federal government had no right to exercise powers not specifically delegated to it; should the federal government assume such powers, its acts under them would be void. Thus it was the right of the states to decide as to the constitutionality of such laws passed by Congress.Anything the federal government attempted that was outside the direct verbiage of the constitution was an unconstitutional act; and it was up to the states to enforce this if the federal government failed to do so.
Time for these principles to be exercised again.