The GOP exploits terrorism because the GOP is and always has been bankrupt morally and intellectually. A rich party monetarily, the GOP is utterly bereft of ideas or hope. The GOP encouraged fear of communism and was, arguably, it's sole beneficiary. Even so, the GOP, increasingly radical under Ronald Reagan, raised other bogey men: drugs, porn and terrorism.
GOP efforts against porn and drugs would fail, it's own membership being among the worst offenders. With the collapse of the 'Soviet Union', the GOP would be left with a single bogey man: terrorism!
Terrorism is the new bogeyman, the 'ringer' for a communist threat that probable never existed but is beyond credible exploitation. Terrorism is much, much more: it is an ill-defined and incredibly convenient pretext by which the GOP may wage an Orwellian perpetual war, in fact, a series of oil wars, that John McCain says may last '10,000 years'. Terrorism, moreover, has become the convenient means by which all opposition to our fascist regimes are marginalized, demonized, and, in worse cases, silenced forever. Draconian measures insisted upon by Bush authorize him to incarcerate without charges, phone calls or habeas corpus anyone suspected of being a 'terrorist'. That means the 'Bill of Rights' is dead. It means the separation of powers is dead! Coupled with his use of 'signing statements' to rewrite laws, Bush rules by decree.