The last time a young politician oozing with charm and charisma assumed the presidency was 1961. The American public was enthralled with John F. Kennedy and continues to rank him one of the best presidents in history.

Historians have not been as kind, deeming JFK one of America’s most overrated presidents. They give him credit—probably too much—for his handling of the Cuban missile crisis, but poor marks for the botched Bay of Pigs invasion and his scant legislative record. But even such historical judgments may overrate Kennedy, who almost triggered a nuclear war for no strategic reason, largely so he would not appear weak before the important 1962 midterm election.

Ronald Reagan also was popular and charismatic and is overrated by the public and experts alike. During his presidency, public opinion polls regularly found Reagan more popular than his policies.

After leaving office, he attained almost mythical status among conservatives and even won praise from liberal historians and journalists, despite selling arms to sponsors of terrorism to ransom hostages and his secret undermining of the major remaining constitutional power of Congress—the power to fund federal activities—during the Iran-Contra affair.

Reagan also cut and ran from Lebanon after a suicide bomber killed 241 U.S. service personnel. And he doubled the size of the federal government, most of it—contrary to popular belief—with increased domestic spending.

Yet Reagan’s carefully cultivated conservative image—a western cowboy on horseback, funny for a man from Illinois—has endured, mostly because, as luck would have it, the overextended and economically dysfunctional Soviet Union collapsed soon after Reagan left office.

Theodore Roosevelt, another colorful macho president, also has been overrated by historians and the public. A manly outdoorsman who was a war hero, big game hunter, and real-life cowboy, Roosevelt captured the fancy of the nation and has been a favorite of historians ever since.

Historians have called Roosevelt the first modern president—a euphemism for a presidency stronger than the nation’s founders intended—attributing a significance to him he doesn’t deserve.

In fact, Roosevelt was much less important to the presidency than his bland predecessor, William McKinley, who used the Spanish-American War to subsume policy-making power from its historical repository in Congress and pioneered the use of presidential speeches around the country—that is, inventing the “bully pulpit” to pressure Congress to do his bidding.

The fact is, journalists and historians love colorful and charismatic presidents, churning out bucket loads of books on such presidents, while shortchanging many others.

Barack Obama has all the qualities these writers and analysts love.

His charisma and “cool” will help him remain popular longer, and give him an edge in his inevitable confrontations with Congress. They should also enhance his historical legacy since even supposedly analytical historians are people too and get swept up in the passions of the time.

But charisma and cool and other characteristics that typically impress journalists and historians—such as the handling of crises, public speaking abilities, and a take-charge “presidential” management style—don’t make a great president.

Presidents should be judged only on outcomes—that is, presidential policies—that affect the country and set precedents for subsequent chief executives. And those policies should be judged by whether, and to what degree, they promote peace, prosperity and liberty.

Barack Obama has all the qualities the public and historians love. Only time will tell, however, if his policies meet the test of a great presidency.