I couldn't agree less. The 6-series and, even more, the M6 likely isn't the only, but used a a second or third car. If someone chooses a convertible of that class, they most certainly want that car to look like a convertible as well, even with the top up. In other words, the advantages of a hard top are less important for big convertibles than the aesthetical advantages of a soft top. Also, Rolls Royce or Bentley would disagree that soft tops make for a 'cheap' car.
Best regards,
south