You are right; the masses do not have the thinking power to decide what is right and what is wrong; therefore the concept of Khilafa or Imamate.
I'm not against implementation of the sharia; any muslim in his right mind will not oppose sharia. It has even been unanimously agreed by all the ulema of all the sects in pakistan that the sharia should be implemented in accordance with the constitution of 73.
The problem is that although the ulemas agree to implement it; problems exist in lower levels of implementation; will the barelvis agree to be governed by deobandis or the opposite? Or will shias accept to be governed by the sunnis or vice versa? I know the argument will be that majority rules. Will that satisfy the minorities that they will not be undermined in the system? Lots of questions still remain to be answered; and how will you gauge the sincerity of the technocrats and the intellectuals?