Of course there's a benefit; you can buy the iPhone 5 for $600. If you would be happy with it this year, you'll be happy with it next year too. The existence of an iPhone 6 doesn't make the iPhone 5 any worse.
I understand this. But most people do not, and will buy the most recent one and wait two or more years before buying the next one. They buy the most recent one, aka the most expensive one, because they believe (correctly) it will last them the longest. But the price changing doesn’t affect their decision.
