Actually, building straight down is substantially easier than straight up.
You are incorrect with your statement about "the way stresses work". The reason it is substantially easier to build straight up is due to our implicit basis where up is towards space. This is getting rather high level but stresses are actually tensors and hence are dependent on the chosen basis. If your basis has up pointed towards the north then it is substantially easier to build a different direction than up.
This may seem like a semantic argument but it is actually an extremely important distinction when discussing any tensor (position, velocity, stresses).
You are incorrect with your statement about "the way stresses work". The reason it is substantially easier to build straight up is due to our implicit basis where up is towards space. This is getting rather high level but stresses are actually tensors and hence are dependent on the chosen basis. If your basis has up pointed towards the north then it is substantially easier to build a different direction than up.
This may seem like a semantic argument but it is actually an extremely important distinction when discussing any tensor (position, velocity, stresses).