The limiting factor is the testing and integration, not the new technology. if it takes X years to do sufficient radiation and integration testing on new techn

The limiting factor is the testing and integration, not the new technology. if it takes X years to do sufficient radiation and integration testing on new technology, you can't possibly include any technology "newer" than X years old. And trying to keep yourself open to include the latest-technology-you-possibly-can means you need to have manpower ready to do that testing at the last possible moment, which has scheduling implications on everything else. So you need to prioritize which technologies you most want to be able to integrate in their latest/greatest form. And slightly fancier pictures are just not going to be that high on the list.