Criminals should be banned from office because they cannot be trusted. Criminals would be more prone to take bribes and steal public funds. They are also more likely to violate the rights of the people. Criminals may even show up to work drunk. Finally, criminals are known to abuse drugs.
How can a voting public ever trust someone with a criminal record to run for office? If someone has a record other than traffic tickets or minor misdemeanors, that person should be unable to run for public office in an election. Laws prohibiting former criminals from seeking office take the guesswork out of whether or not voters can trust the person and sanctify the electoral process so more "honest" candidates can run for office.
Sure many criminals are untrustworthy, but some are. It is up to the public to decide if they want a criminal in office. Perhaps the person has served a year in jail and feels that we need to increase the budget on security to protect prisoners from other prisoners. If we do not give them a say, it is undemocratic and the viewpoint is suppressed.
Terrible idea. America has the highest rate of interment in the world. The criminal code is undeniably designed to burden the poor and minorities. Criminal justice has been warped by revenue generation at the private and public levels. To systematicslly bar such people from running for office further restricts individual liberty, reinforces the unsustainable status quo in criminal and economic justice, assumes voters cannot discern information on their own, and limits the ideas put forth in public discussion.