Looking past the artwork, it keeps another low-production CHRYSLER convertible alive.
As for "the canvas", obviously, a flat canvas was needed. '67 Buicks had more curves and a shorter deck lid. Cadillacs had the length, but too many body lines and chrome in the way. Mercuries, too many body lines and curves. The Chrysler won by default AND the fact it was still around/available/durable.
Nothing some paint remover and a repro interior can't fix. Plus a set of Magnum 500 wheels and some quality narrow-stripe white walls.