How are you so sure? I had a buddy wait forever to get a white iPhone. He was so happy, went as far as calling it better than the black versions. Think that's stupid? Yeah, me too, but it proves my point. He did it specifically because everyone had black iphones and he wanted to be different.
So give me a few examples of yourself, or someone specifically where it makes sense for them to use a 5.5in phone?
People who...
Play games frequently
Browser the web a lot
Stream Netflix Hulu, ESPN, Amazon, etc.
Browse family photos and often show to other family members
And just about anything where a larger screen is useful.
All the above and much more for someone who,
Doesn't want to lug their iPad or mini around in addition to their phone.
Doesn't want to pay separate data plans.
Doesn't want to pay extra for LTE iPads.
Doesn't want to tether their iPad due to battery problems (and its annoying).
People who can carry the "phablet" in their bags/purses (especially women).
Older people with poor eyesight (My parents switched to the Note from an iPhone for this very reason. And they really enjoy it. No, they didn't get it to be "different").
People who don't like taking their iPads with them everywhere, yet enjoy the benefits of a larger screen.
Again, it comes down to what size you can tolerate for the inherent and very clear benefits of a larger phone. I personally wouldn't mind having a 5.5" phone because I know I'll enjoy the benefits and are willing to sacrifice mobility, and I'm always looking at my iPhone 5 anyways. It's rarely in my pocket. I leave it on a stand at work, I leave it the cup holder in my car, I leave it on the table when eating, etc.
I know you don't find the benefits of larger screen desirable, and I don't judge you. In fact I understand why you like smaller phones. But, why is it so hard to understand why I don't mind carrying a big phone? And that it's not because I just want to be different? If anything in this day and age, having a small phone is being different. Even Apple is somewhat admitting so.