Interesting thread. I have plenty of fit issues, but I don't think of myself as disproportional. That might be due to having watched a lot of online videos about Kibbe's body types, which seem to me to embrace more diversity than what we see in off-the-rack clothes.
I have heard that clothes are generally cut very straight because it is much more difficult to sew curves--and therefore more expensive. So in short it is cheaper to produce clothing that is made for a straighter body.
Finding tops that fit is a huge challenge for me because my waist is so short and my shoulders so narrow. So inevitably excess fabric ends up at my armpits, and I feel the shoulder seams on the outside of my shoulder (not a comfortable feeling). The waist, which is the smallest part of the garment width, will hit me at my high hip, which is one of my widest spots due to my figure 8 shape. Nothing will make me look frumpier than a misses'-cut top!
My solution is to shop petites' as much as possible, though that can be pretty boring. I have had success buying some form-fitting *knit* tops (turtlenecks, tees) in misses' sizes, as long as the sizing runs small. I have some turtlenecks from Club Monaco and some tops from Reformation that fit me well. Anything woven and tailored is likely to be a disaster unless specifically cut for a petite.
When I'm shopping misses', high crew necks and turtlenecks are good styles, because they help hold the shirt in place (if it's a little too wide in the shoulders, it can shift around). I avoid V-necks and scoop necks, because the neckline will be scandalously low. When shopping online, I have also recently started looking at the back view of the model, to see roughly where the shoulder seams hit her and whether she is an inverted triangle (many models are). If she is an IT and the shoulder seams are accommodating her nicely, I just assume that the top will not work for me and I pass on it.
The struggle is real!