What has changed in peacekeeping since traditional peacekeeping is the expansion of mandates, which means that you need all kinds of people who have skills in those areas. If you're dealing with nation-building or security sector reform, you not only need to reform the military and the police but to deal with the courts. You even need to deal with the intelligence agencies of the government.
That requires specialized capacity, and that's where our reservists can help, because from their regular jobs they may bring in skills. That's why we need to do specialized training for these kinds of activities, with the wide range of mandates the UN is giving.