I’m not sure what you mean about their not bothering. The Mark XV is from 1999-2006, and before that, ETA/Stellita movements weren’t used. Since then, ETA/Valjoux/Stellita sourced movements have been similarly finished (few component changes, perlage, some striping on visible surfaces, etc)albeit without the gilt. I guess I’m just asking which references you are referring to, as I’m not familiar with any time that they didn’t do that level of finishing to their sourced movements. I’m aware that the supplying companies do some of the finish work so that it’s not all IWC per se, but I don’t think IWC have ever just dropped a raw third party movement in a watch and sealed it up for sale.
Thanks for your time,
Brian