I’d argue any insurance should cover its current market value, not some notional value determined by the carrier/insurer. Otherwise, I agree, the insurance is not worth the paper it’s written on (or not, in today’s digital world!).
Bear in mind that you might want insurance not only against damage, but against the item going missing. Under such circumstances, you might find you could open a legal claim against the shipper, but that is a pain and the laws vary country by country.
Thanks, Angus. Really useful to know 
I ordered this wrap for future sales/shipping:
Hi All,
As a rule it’s always best to “hide” the identity of any items being sent via any means (post, courier etc.) but if the couriers insurance specifically requires this then it should state it in their T&Cs otherwise they can’t just add it as a requirement after the event.
Of course that does require the T&Cs to be read rather than just ticking the “I have read the terms and conditions” box and I probably do exactly the same as everyone else there… 
Phil