That means you are probably using a limited set of lightweight apps. Or maybe competing for the longest lasting S3 award :P Usually, people tend to install more and more apps and those apps themselves are getting more and more resource hungry. That's what's driving the higher and higher hardware requirements and that's how the manufacturers survive. This is not even Android or iPhone specific pattern, this is true for all my laptops as well. Several years ago a dual-core 4Gb ram laptop felt like a hell lot of power and now, with Docker, VirtualBox, tonnes of services running inside of them, and a video call on background, my i7 16Gb macbook feels like a turtle.

Add: Skype, I think is a great example. I used to use it (maybe through immo.im) on Nokia 5233 and it was fine. And today Nexus 6P is getting hiccups.