A person should still vote, even without research into both candidates, because it is nearly impossible to be so sheltered that you don't at least have a passing opinion on the subject. We need all people in this society to vote, informed or not, on the president of the United States in order to have ALL represented.
Yes, a person should vote even if they haven't researched the candidates. A person should never forfeit their right to vote, leaving others to make the decision for them. However, that doesn't excuse an individual from making an informed decision. It's important to know what you're voting for and then to vote as well.
No, I do not believe that a person should vote if they have not done research on the candidates. Although voting is a basic right for the citizens of our country, that doesn't mean that everyone should vote. If someone can't take the time to learn about the election and they are just placing their vote because someone told them to, that is really a shame to our system.
There is not a "moral obligation" for citizens to vote, the reality is that not everyone should vote. Voting is just one of many ways we, as citizens, can exercise our civic virtue. Voting is an act with major social consequences for the community as a whole so we should not vote unless are an informed voter who can vote responsibly.