I hear ya on those designer sizes. My theory is that the overwhelming majority of buyers are old people and they have smaller feet. I remember when I was really young, the biggest shoe aisle at Payless was size 7. Now the size 8 is the biggest. Also, just a few years ago, there was barely a selection for size 10. Now there is a nice half-aisle.
The overwhelming majority of women I know are at least a size 8. So yea, I don't get why expensive shoes are so small. Same with clothes. Maybe it's different in New York but here most Neiman Marcus patrons seem to be, again, old people.