What could be done is having the optimizer only use standart (or easily constructed) parts, only optimizing the design.

So you could say "oh, this structure supports these forces and it is assembled with 50cm and 25cm beams, optimize away".

Of course, an engineer can solve simple cases easily, but as you join compression and stretching forces in weird shapes it can get complicated fast.

Examples out of my head: stadium ceilings, small tools that are required to be strong in a specific way, bridges with limited foundation places, etc