you're right that playboy Bruce and clumsy Clark are designed to throw people off, but i also believe that these "fronts" are merely a sliver, or perhaps an over-exaggeration, of the more complete personas of the real Bruce Wayne and Clark Kent.
Bruce is a charming man, regardless of his wealth, and as he is the son of his father, has a true noble heart that any woman would be proud to have her arm on. but Bruce's psychosis keeps him from holding down any kind of lasting relationship. Clark truthfully can be incredibly clumsy, in the JL animation he once said that living on Earth amongst humans is like "living in a house of cards", always having to be mindful of the strength and consequences of even the most mundane actions. and lets be honest, Clark is an alien that has reached an advanced development only humans dream of achieving, so certain tell-tale signs of being a little too strong, aka clumsy, or a little too smart, aka geeky, is fully expected of one supra being in a world where everybody else is not quite on the same level as he is.
and to give credit where credit is due, the Nolan and Singer films have succeeded in showing the complete characterization Bruce Wayne and Clark Kent even if they were only in brief moments-- Bruce whenever he's with Alfred; Clark when he was at the farm with his mom. i'm hoping that they can continue this trend of putting out there the "totality" of a hero and not just focusing on one facet of personality or the other.