The advantage (?) is that one can go to wider tread/lower
profile and still end up with the same rolling radius for no
speedo error.  (usually it's close rather than perfect).
This is called "plus one" when going up 1 inch wheel size.
(And also some folks feel when installing really pretty
wheels the more of the pretty the better.)

URL for tire size comparator:
http://www.dsm.org/tools/tiresize.htm

This will indicate, having entered 184-14 (185/80-14) that
205/70-14 and 205/65-15 all have nearly the same rolling
radius.  15-in wheel provides more room for brakes.

Probably others have more ideas (besides looks & room for
brakes) why larger diameter wheels may be better.  This is a
pretty good question, because it's going to be really hard
to find/retrofit larger brakes.  The brake advantage
probably only applies if you're designing a new vehicle.