[T]his idea of picking your year doesn’t make much sense. There’s a ton of uncertainty inherent in any presidential campaign because the dynamics of primaries are very hard to predict, and because the underlying economic trends that weigh so heavily on general elections are also hard to predict...Have Republicans waged a primary campaign, then lost, and gone on to have successful future political careers? Yes. The conclusion is clear—he should get in. Unless the issue is that he doesn’t actually want to be president (understandable, in my view, though I would love the airplane) in which case he should shut the door on this.I agree! Now, you might say -- wait, Plain Blogger, weren't you just ridiculing a Jon Huntsman campaign? The answer is that the cases aren't at all the same. Huntsman, at least in my view, has no chance to win the Republican nomination for president in 2012. His issue positions, and his actions, have made him an entirely illogical candidate. The only such nominee during the modern era was, perhaps, Jimmy Carter -- and Carter would have had no chance under the system as it evolved after 1980.
Thune is very different. Right now, he's just a generic statewide elected official. There's no particular reason to think he'll win, but then again there's no particular reason to think he won't. Such candidates mostly lose...but only because there are lots of them, and only one nominee per cycle. And sometimes they win, as Mike Dukakis did in 1988.
Now, that doesn't mean that there aren't good reasons to wait, but generally they should be personal, not political, reasons. Mounting a serious run for the White House is a huge, life-consuming effort that presumably almost no one enjoys. It puts your entire family in jeopardy of having their darkest secrets splashed all over television (or the stupidest thing they're going to do getting taped and going viral). It means being open not to the friendly press of South Dakota, but to the collective attention of the national press (and all sorts of nastiness from partisan, and even intraparty, rivals).
I could also imagine political reasons involving the rest of someone's career; for example, a Senator might want to avoid running in one cycle if it meant giving up his or her seat. Running may, too, pose some risks for reelection, so if staying safely in office is a priority, then the longshot chance of being winning or even being nominated might not seem worth it. If a candidate has good reason to believe that he or she will be a much stronger candidate in the future -- say, a Member of the House who can move up to the Senate -- then waiting makes sense. That's about getting stronger oneself, not waiting for a better year.
But I fully agree that waiting for the cycle in which a candidate has the best chance to win is a fool's game. For all anyone knows, next year could be like 1980, and the nominee and runner-up will hold the nomination for the next three cycles, making 2028 the next real opportunity. Figuring out how the dynamics of the field will work this time around is really impossible right now (will Huck be involved? Palin? Perry?), let alone having any sense of how it will compare to 2016 or 2020. If you're ready to run, run.