Max Hughey respectfully submits the following (and cites Willy the
Shake to prove that he really means it):

Ban “sea change” until people learn its meaning.
It does NOT mean a watershed event but, rather, indicates a miraculous
change into something finer, such as from a grain of sand into a pearl.
(See Shakespeare’s “The Tempest,” Act I, Scene II; Ariel
sings, “Nothing of him doth fade/But doth suffer a sea-change/Into
something rich and strange.”) For example, the 1994 Republican
takeover of Congress was NOT a sea change — unless one is a Republican
— although I’ve heard it used dozens of times on radio and television.
One might almost believe that this usage has been orchestrated by
Newt Gingrich et al.