In defense of the professional politician
Being a professional politician is not in and of itself a bad thing and can be a reason to support a candidate. Too many candidates for office run on the basis of not being a "professional politician," a statement calculated to win voters with an emotional appeal rather than a substantive argument. We're seeing this pop up again this year, as we do every year.
Now, we have all heard the yarn about the politician who has been in office too long and is only interested in protecting his career or personal interests instead of the principles he was elected to implement in the first place. This is why voters need to continually pressure elected officials to make sure they are holding the line. But that is a function of a person who is not sufficiently devoted to his principles, not someone who has been in office too long.
In a legislative position, with all other things being equal is it better to have someone who understands the legislative process, has a powerful committee assignment due to seniority, and has relationships with other legislators that will allow him to advance legislation? Or is it better to have someone who has none of that? He may vote the right way, but will not be able to accomplish as much as the dreaded professional politician.
Again with all other things being equal, is it better in an administrative office (such as a state treasurer, county sheriff or city clerk) to have someone with managerial experience and extensive institutional knowledge of the operation of county, state or city government in addition to qualifications for the job itself? Or is it better to elect someone who is "not a professional politician" and will have a learning curve upon taking office?
(As for the President, I do not buy the argument that he needs executive experience. The President is not an administrator. If the President ever actually had that role, it expired a very long time ago.)
There are many things to consider when we are voting in a primary or general election. Years of experience in elective office is one of those considerations, and experience should be seen as a positive. In no other field do we consider experience to be a bad thing - as anyone just into the job market looking for their first job will tell you. We have it backwards when electing candidates for office.