The credit value of the block is not the issue. It's the time element.
It's 20 times faster to shop than salvage (not even including the time needed to process the raw materials into parts). So, if you have 3 to 4 hrs a day that you can play, would you spend that limited time salvaging asteroids or shopping to obtain your required parts you need to make even a small ship (at the ~250 blocks per hour rate of salvaging and then crafting vs ~4000 per hour shopping). Either way, you're not going to build a titan sized ship in a short period, but I know which way my limited time will be spent. A higher yield for your salvaging efforts (more raw materials and shards per asteroid) is the only way I can think to make it viable time-wise and not ruin the actual crafting systems that is there, and now works.