Well part of why it does so well even amongst those in the know is because Samsung consistently includes what we want even more than a nicer looking design.
Things like better battery life, removeable batteries, better specifications, microsd storage and so on. I love the look of the HTC One and its front facing speakers but almost everything else, Samsung beats it out.
In the end, I'd rather have a faster phone with better battery life and removeable storage over a nice looking phone that doesn't have all that.
That is part of the problem, people are making a conceptual fallacy about battery life and storage.
What people really want on their phones is more battery life and more storage. There are several ways to address that problem, higher capacity batteries, more built in storage, swappable batteries/storage, etc.
The fallacy is that people seem to think the ONLY way to achieve the primary goal of more storage and more battery life, is to allow those components to be swappable. No. You could increase the base level storage of the device, like the ONE did. If people need even more than that can provide, then they would need to go to a phone with swappable storage. How many people do you think that is?
For battery life, that is even more of a red herring. The primary reason people wanted swappable batteries, is that battery life was so god awful (think HTC Thunderbolt) you needed to swap them out to get through a day. But there are many phones that can easily get through an entire day on the built in higher capacity batteries. I have an s2 now with an 1850mah battery, the ONE has a 2300mah, the s4 a 2600mah. I can already get through the day fine on my phone unless I am using data all day. So what is exactly is the outsized benefit of being able to swap the battery? to let the phone last longer playing some 3d game on the phone I don't care about? And even if I wanted to do that, there are external chargers, and battery cases with FAR more storage than ANY of these swappable batteries.
It is a non issue, a pebble in the road that would deter almost no one from being able to use the device, but some people turn that into a redwood sized barrier that makes the phone useless. It is not logical. They are confused, they think the goal is swappable batteries, and swappable storage. No. The goal was sufficient battery life and sufficient storage, and making those swappable is not the ONLY way to get there.
easy analogy is an electric car, takes a bit of time to charge, however, if there were batteries that existed that were cheap enough and energy dense enough for a car to travel 1000 to 2000 miles on a charge.... a longer charge time would NOT be that big of a deal. The need to SWAP out the fuel so frequently would not be a deal breaker.
Am I making sense here?
I get that people have priorities of swappable this, and swappable that, but I am telling you all, you are focused on the wrong thing.
If you had a phone with a built in battery that lasted 4 days on a charge, but the battery was not swappable, and you chose the s4 over that even though you liked everything else about that other phone, that would be extremely foolish. Are we there yet? No, but we will be, and I need some of my faith in humanity and reason and logic restored, I need to know that at some point people will stop being so obsessed with trivialities like swappable storage, because at some point, they will become trivial issues for everyone. They already are for many, but the momentum of a tired and decayed idea often lives far longer than its shelf life.