It's an axiom that's as old as television itself (maybe even older), but it's true: former presidents are much better interviews than sitting presidents. The reason isn't rocket science: an ex-president doesn't have to watch what he says, he doesn't have to worry about being re-elected or burning political bridges.

This is the big reason why I'm looking forward to Matt Lauer's interview with George W. Bush tonight, which airs at 8PM ET on NBC. It's Dubya's first interview in support of his memoir 'Decision Points,' which will be released tomorrow. From what I've read and seen in various sneak peeks, it's going to contain some interesting admissions from one of the most polarizing Chief Executives this country's ever had.

But, according to Brian Stelter in The New York Times, Lauer will not be grilling Bush on what went on during his eventful presidency. "The tone of the prime-time special is conversational, not prosecutorial," wrote Stelter, "and for that reason, "Lauer/Bush" is not likely to join "Frost/Nixon" in the public imagination."

That's absolutely OK, though; Lauer doesn't need to lower the hammer on Bush in order for this to be an effective and fascinating interview to watch, for a number of reasons:

He's not president anymore. Even Bush's most ardent critics -- and by the time he left office, there were many of them -- have to realize that it's counterproductive to grill a guy who's been out of office for almost two years. Whether you liked his policies and decisions or thought they were atrocious, what's done is done as far as Bush's presidency is concerned.

I'd much rather hear about his thought process behind some of the decisions he made, as well as how he was conflicted or if he went through any emotional turmoil, than listen to him be goaded into admitting he made a mistake. For instance, Bush told Lauer that he was a "dissenter" on the decision on whether to invade Iraq. If that's true, wouldn't it be interesting to find out how his opinion was changed by Dick Cheney and other members of his team? At this juncture, it's much more fascinating to hear about the behind-the-scenes machinations of a presidency from the man in charge rather than continue to grumble about decisions that were made years ago, as costly as those decisions may continue to be.

We'll find out what kind of ex-President Bush is going to be. Bush has mostly stayed out of the media spotlight since he left office, doing personal appearances and going to Rangers games. Unlike Cheney and Karl Rove, he refuses to openly criticize President Obama, and will likely maintain that stance. But this interview, and some of the other ones Bush will do to promote the book, will go a long way to letting the public know what kind of ex-President he's going to be.

In the era of electronic media, we've seen all sorts of ex-presidents; ones that rarely if ever made public appearances (Gerald Ford, Ronald Reagan), ones that became more stately and dignified than when they were in office (Richard Nixon, George H.W. Bush), ones that loosened up (Bill Clinton), and ones that felt free to criticize those who were currently in power (Jimmy Carter).

Judging from another preview of the interview, where Bush tells Lauer he came to his pro-life views after his mother had a miscarriage and showed him a jar containing the ill-fated fetus, it feels like Bush wants to open up a bit. He showed that element during his presidency, but that desire to open up may now extend to how he felt as he made those nation-changing decisions after 9/11.

There's enough political rancor on TV these days. This interview, and Bush's responses, will be picked apart and scrutinized for days after it airs. Fox will likely think Lauer was too tough on Bush, MSNBC will likely think Lauer lobbed softballs, CNN will likely put up a silly graphic to show how neutral they are. Lauer will play the interview down the middle of those two extremes, which, according to Stelter, is why Bush's people picked him to do the first interview. "We're living in a time when some of television news is partisan," 'Today' executive producer Jim Bell told Stelter, "and Matt and the 'Today' show are decidedly not so."

I'm looking for an informative interview, one that gives some insight into the mind of a guy who used to be the most powerful person in the world. If Lauer plays it as down-the-middle as these previews suggest, viewers are going to get just that.

What do you hope Lauer and Bush talk about during their interview tonight?

(Follow @joelkeller on Twitter.)