From the end result described either they didn't try or they weren't successful in doing it. If they did there wouldn't be any changes made to appease the customer.

The fact that the customer was buying 3d printed computer optimized parts in the first place probably indicates that "more advanced" was explained to them.

There are any number of reasons they might not have liked it. Maybe it looked odd because it didn't match the rest of the design. Maybe they were worried about their own customer (of the end product that the part goes into) thinking it didn't look sturdy enough.

If you're designing parts for a rocket then by all means worry about every ounce of weight, but for most stuff if the customer wants it to look less weird you can just make it look less weird. And then charge them for the extra material.