To love someone doesn't mean you have to agree with them. A mom and pop cake shop in AZ shouldn't have to make wedding cakes for 2 women who want to get 'married.' But they can still love the women as people.
People buy the iPhone for iOS and the iPhone build quality.
We are limited to a 4" screen because that is the only thing that Apple offers.
To make this comparison to Android phones based on screen size is silly. What it says is that, given the option, most people prefer a bigger screen.
What this tells us is that Apple is behind the curve. There are a few supply-chain-based rumors on here already claiming a big-screen iPhone is in the works for next...
If I buy a washing machine......they pretty much all look the same.
If I buy a TV.........they pretty much all look the same......a black rectangle, but with a different company logo on it.
Smartphones all pretty much look the same, since they're almost all screen. GPS units pretty much all look the same, and you don't see lawsuits among them.
A tablet is a hand-held screen. It's basically a rectangle. Not much to improve upon, or to differentiate...