A divided government is the best option for the citizens to have a voice within their government. It promotes debate and prevents things from getting too much out of balance. It also helps to prevent tyranny within a government because it increases the likelihood of an opposing voice, which promotes more debate.
When you have a one party government, it is always one possible outcome. No ifs, ands, or buts about it. What that one party says, goes even if they are very wrong and that decision ends up hurting them and their country. Even if it is bad for the people of that nation. With a divided government, there can be multiple outcomes and that comes from different opinions. They voice the options, opinions of others and the ones that they represent and usually come to the decision that is best for their people.