What I find kind of funny is Windows has gone through this exact issue with their Windows Phone platform.
The Lumia lineup started out okay with a flagship device (920) and mid to high range device (820) a mid-range device (620) and a low end device (520) and a nice photographer device (1020). Things started getting really blurry with things like 925, 930, 635, 730 (can't remember them all) and suddenly a lower number device actually had better spec or almost similar to a higher number device, or the specs were so close together that it looked really confusing. Not to mention people begging for certain models to be upgraded and it never happening meant angry customers.
To me, it looks like Apple is slowly making the same mistake albeit a lot slower. You would have thought they were paying attention and wouldn't go down this route.
The Lumia lineup started out okay with a flagship device (920) and mid to high range device (820) a mid-range device (620) and a low end device (520) and a nice photographer device (1020). Things started getting really blurry with things like 925, 930, 635, 730 (can't remember them all) and suddenly a lower number device actually had better spec or almost similar to a higher number device, or the specs were so close together that it looked really confusing. Not to mention people begging for certain models to be upgraded and it never happening meant angry customers.
To me, it looks like Apple is slowly making the same mistake albeit a lot slower. You would have thought they were paying attention and wouldn't go down this route.