The value of the damaged one (before the damage, obvioulsy) absolutely matters, as that is what the airline is liable for. Mine was nearly new, but the guy would only give me a credit of less than half its purchase price to be applied to a new purchase of one in his overpriced old stock. No purchase, no certificate.

I had no interest in paying him €350 for a suitcase that had been sitting in his shop for nearly a decade. By law the passenger should be made whole, whether by repair, replacement, or compensation. Blackmail is not part of the equation. If repair or replacement without cost was not possible, then I wanted compensation. KLM would only pay compensation if I provided a certificate from their contracted shop saying it was unrepairable. But the contracted shop refused to issue that certificate unless I bought a suitcase I didn't want. He was trying to make a lot of money by forcing me to buy something I didn't want, while keeping KLM as a happy customer with a liability of only €70 something for my damaged suitcase.