Populism rewards short-term thinking at the expense of long-term results, because the common person isn't always aware of the deeper issues in a given field. Put another way, would expect the average person in the street to have an informed opinion on the details of [banking|medical|energy|transport|agriculture] industries?

We already know how easy it is for yellow journalism to sway popular opinion; expecting direct democracy to be able to deal with the subtle nuances of governing a millions-strong society is nice in theory, but simply isn't practical.