None of those dresses are styles that I would have wanted to wear to my wedding, and since I'm 6' and had to have my dress cut super long, I wouldn't have been able to buy them, even if I liked the styles.
I suspect that it will be the same as with cake. People who are going to be buying Target wedding dresses were never custom dress makers' customers.
Spending money on a wedding isn't always about showing off. Sometimes it's about having the experience for yourself, or about spending money to buy a quality item, where you value quality in that item.
I spent $1700 on my dress, I felt amazing in it, I have beautiful photos, I'll never wear it again, and I'm glad I spent every cent of it.
Not all of us are lucky enough to have friends or relations who are DJs or bakers, or dressmakers whose skills we can take advantage of.