A better comparison is that Windows 8 runs faster than Windows 7, which in turn ran faster than Vista. Linux kernels continues to improve in performance too.
There was a talk at WWDC this year (session 419, if you want to watch it) that goes into some detail about how the blur effects on e.g. the lock screen, notification center, control center, toolbars, etc. work.
You can watch the talk for the details, but as a practical matter several of these effects involve seven (!) full GPU passes, just for these effects alone, let alone whatever UI is under or over them. And not even the very latest-gen devices can do it consistently full-screen at 60fps. iOS displays motion underneath blur effects in very small areas (e.g. a toolbar) on new devices but if you think about it, you never see motion underneath, say, the lock screen. The reason is that not even the latest iPad Air has the GPU to apply some fullscreen blurs in enough time to meet the draw deadline.
This actually surprises a lot of people--I can't count the number of designs I've gotten where some designer has made a large blurred UI element and expects something to move underneath it. Which, depending on the size of the element and the target hardware you can sometimes get away with, but you are in for quite the lengthy performance test, and a complicated spectrum of fallbacks for all the devices that just aren't fast enough.
And that's just one blur effect. You take a look at all the other "new" iOS things that are less visible, like the endless stream of new background technologies (background fetch, silent push, NSURLSession, multi-app audio routing, various iCloud syncing stuff) the new bluetooth stuff (iBeacon, HomeKit, Multipeer), turning WebKit into an LLVM compiler, and all the other things that are going on in iOS it really is "doing more of everything". I remember a time when iOS was basically just a few OS processes plus 1 active app, and as we speak ps on my phone lists 87 processes.
At some point in the "near" future it'll be energetically a net positive to snap a pix on the cam, analyze the eye pupils and accelerometers and recent eyeball movements, and if you're not looking at that part of the screen, its not going to waste energy displaying it. Could even see this happening with backlighting. Watching other people use their phones is likely to get very distracting for 3rd parties.
There are often better explanations. GMail is fast. All the time. No matter how much mail you have. That's because it runs from a local database and all server interaction is abstracted behind sync and local accesses to data. Google Play is slow because it is a REST app with a native app veneer. It's harder to make an app like Google Play use sync'ed databases. So sometimes it does puzzling things like taking tens of seconds to go to the next track even when you are shuffling only your downloaded music.
Fast apps can "do more" and remain fast. Slow apps are slow for architectural and algorithmic reasons rather than because they "do more."
I don't know about Android, but on iOS, the Gmail app is much slower to launch and navigate than the stock mail app. I think that, on launch, the Gmail app makes some requests before showing you any of even your locally cached data, which always struck me as poor design.
I think the google trends graph for "iphone slow" search phrase says all that there's to say about this phenomenon.
Also, with each iphone generally comes a new ios version, which is more or less written for the specs of the newest phone. That being said, this post is being typed from an iphone 4s I've owned for two years. I've never had any complaints about performance. Never noticed a slowdown.
Second, we do studies like this so that one data point (yours) is not used to make general understanding.
The term OS, as it is used by media and most people today, is the software that is installed on the device before you install any additional apps to it. E.g the "App Store" is considered a part of iOS, the Internet Explorer as part of Windows, and the Homescreen and Dock of Max OSX is considered a part of OS X.
Since a Galaxy and a HTC One ship with different Applications, a different user interface and other key software components (you mentioned the filesystem on the Galaxy S), Android is less an operating system but but the cross platform foundation that most operating systems are based on today.
Presumably youre implying here that people who complain about their iphone being slow are the people who upgraded their OS while keeping their old hardware?
Samsung is just a generic hardware vendor for Android PCs, like Dell. They don't create operating systems or apps.
It probably also has a psychological component. Just seeing a new generation gaming PC makes mine feel slow.