Bottom line: would the humble, supportive Clark from Smallville independently decide to wear a cape? I somehow doubt it.
He would if it were part of his Kryptonian heritage, which is how Mike Grell answered that very question in his excellent Trinity
miniseries. One caption: "My people wore capes."
Moreover, if you think about Superman's costume, like in Superman: The Movie
and Mark Waid's Birthright
, as a piece of ethnic grab than the cape makes sense. But it does make perfect sense because it looks so aesthetically pleasing when in motion as Superman flies or hovers or moves faster than a speeding bullet.