I sincerely thought there could be no way for an iPhone dedicated thread to appear here, but let me state a few things about all this.
First and foremost, Apple products are generally regarded as luxury accessories that cater to a special, yet broad audience that finds these gadgets as a label of their status or, like in the case of the environment I live it, makes it think that it has a status. Of course, such products are perceived differently from place to place, but I think we can agree that a significant part of Apple's customers don't buy their gadgets solely for their technology.
Secondly, the reason why the mobile market gets over-saturated with new products on a yearly basis is a fierce competition between technology giants aiming to secure bigger quotas to the damage of their counterparts, hence all the new releases.
To wrap this up, my personal opinion is that we don't have too many reasons to get excited about the new X or Y thing, because as the trends reveal, we are not going to witness any technological breakthrough that would objectively justify the acquisition price or the need to buy the new product altogether.
As long as the people will be enthusiastic about the new rectangular box of the year that contains nothing more special than the previous one, I can't see how the companies will be inclined to press the 'research' button more often.