The DOHS was redundant in function from the start, created to make it look like "W" was responding to terrorism in a big way. They've been much more effective at eroding privacy and civil rights than at having an effect on terrorism. Also, have you ever heard an agency name that evoked the Third Reich aesthetic to that degree?
The best antidote to terrorism would be for the U.S. to stop funding and otherwise propping up any dictator, military coup, strongman or warlord who serves their temporary interests. Nobody is more dangerous to our interests than someone who has lost his family, livelihood and home in a way that he has every reason to trace to the actions of the U.S. government. Such a person may feel that they have nothing to lose by sacrificing themselves to revenge.