My basic question is if all these expensive, highly marketed clothes can truly improve the average man's appearance in relation to their cost?
I think they can make a nice impact if put together well. Typically handmade clothes in my experience have nicer silhouettes and last longer and perhaps most importantly wear more comfortably.
Also, off the rack rarely fits anyone well in my experience. More money gets you the made to measure option for a better fit.
Also, in my experience more expensive clothes utilize better fabrics that even if finer like Super 120s and 150s have better durability and better appearance. Styling also tends to be more classic and last longer (years).
Caveat Emptor: Many trendy brands like Armani, Prada, Gucci, Theory are very expensive but not well made, only fit skinny guys, and use often poor fabrics, often with a high poly-fabric content.
Silver lining: there are several brands that offer good value for the money. If you need to spend less then you can still look great.