Prince's lawyers were using whatever angle they could think of. Clearly an attempt to distort the meaning of the compilation concept. A photograph is not a book of trig tables. ... How disastrous it would be if that compilation assertion prevailed.
Particularly since, as the judge in the case noted, it's been a matter of settled case law for the better part of a century that photographs are original works in the meaning of copyright law. To base your defense on a theory that was dispensed with decades ago is really weak.