Sharp angles always introduce an imposing feeling.
Most likely the best kind of stuff to observe this might be "Propaganda Architecture"
Check out North Korean and Nazi-Germany buildings, how they use their size, their few details and sharp angles to really make you feel small.
Mecha-Design works from it's shape language usually on a very similar level.
Evangelion adds imho a feeling of uncannyness to it. You have huge, nearly human shaped mechas, who wear a mask.
Masks are always unsettling in a way and the distorted proportions underline this feeling. On top of that you have design elements which let the whole design look even bigger and in terms of the shilouette a lot more "simplified" and "angular" than an organic lifeform.
It's super-smart and psychological high-levelled design.
One Mecha I could think of which doesn't follow this principle of sharp angles though, would be the one of Sucker-Punch
although ... it's Sucker Punch, which should be enough of an explanation.