Yes there is the concept of free market competitive prices, but with private markets there are generally great externalities. Competitive energy production would suggest that firms would need inexpensive energy sources, like coal, that tend to have a negative impact on everyone in the form of pollution. With central energy generation systems we can lobby for renawable and sustainable ways of energy production.
Electricity should be privatized because that would likely mean better rates for the general public. This would happen because there would be more companies in the business. When more companies enter a business there is more competition. More competition usually means lower prices. So, privatization of electricity would be very beneficial!
Utilities in general should remain public because they then remain in the public's best interested. Once electricity is privatized it allows a monopoly to appear, and suddenly the people are considered in the decision making and aren't at the companies' best interests because it has become all about the profit.
Privatizing anything basically opens the doors for monopolies to form with ease. The last thing we need is one person controlling electricity...something we need to sustain life (kinda). Although government regulated energy is equally as detrimental. It is just the lesser of two evils at this point and it will be irresponsible to change it.