It's nice to be the swashbuckling guy who fights using skill and wits.
From a gameplay point of view, being mobile and doing lots of damage is fun
Which doesn't require being a Rogue. A Dexterity based Fighter with mobility based Feats also fulfills the skills and role necessary for the archetype (at least for a certainty in 3e and 4E, though I think it was also possible even in earlier editions).
Case in point: Athos, Porthos, and Aramis (commonly known as the Three Musketeers) and their young friend d'Artagnan are not Rogues, they are Fighters (Soldiers with applicable armor proficiencies, broad weapon proficiencies, and military training). And they most certainly are archetypical
"Swashbucklers".
If doesn't take a Class to be able to do things with
Flair.
None of which is to say that Swashbucklers can't be Rogues, just saying Fighters can fill the role just as well.
Also (though not addressed specifically to you, Wulfram, but to the thread in general), they most certainly are not about back stabbing or sneak attacks. They fight face to face - with their speed, strength, and wits against their opponents speed, strength, and wits.
Now one can have a Roguish Swashbuckler, like a Pirate Errol Flynn, and back stabbing or sneak attacks definitely fit the character. But back stabbing and/or sneak attacking is not required to be a Rogue.
