As I mentioned previously, my son uses them for flying ... keeps flight logs, files flight plans, fight plan maps displayed on phone. He originally used an iPad but with the ability to use on phones now, the smaller form factor is of great value because in a cockpit, space in your field of view is limited and, the bigger the device, eats up space and often blocks view of instruments and gauges.
6.2 inch S8+ plus here, still pocketable and can handle it with one hand just fine. I genuinely cannot understand why people still complain about this. The matter of the fact is the overwhelming majority of us do want huge phones and can use them just fine.
If you are annoyed by this then I am sorry to say this but your in the minority here, not the other way around and phone manufacturer will always cater to the majority.
As far as the "majority of us" ... it depends on who the "us" is. In the office and on the jobsite, the smaller or what i call "medium" form factors are far more prevalent. Those who use their phones for productivity prefer the smaller from factor by an overwhelming margin. Those who use their phones mainly for entertainment purposes or to occupy idle time, that segment overwhelmingly prefers the larger form factors.
My three sons, all had the larger form factor phones .... the oldest, keeps his phone in his flight bag. The other two, well they both have bent phones from keeping in pockets. They plant to switch to smaller (medium) form factor with next upgrade.
Logical folks should select the form factor that best suits them. Sometimes, what we think we want doesn't work out so well as 2 of my sons found out and a more appropriate choice is made next tie out. In many instances, it's going to me more about impressing their peers than picking what works best.
I find that at a 3" width I am struggling a bit to securely hold the device and reach all points on the screen ... so 2-3/4" is about my limit width wise. Length wise, 5.5" is OK.... 6" is bordering on uncomfortable in my pocket. My wife, she has the iPhone 6 and finds the form factor just right for her.... the 6+ was too big.
But in the end, I am at a loss to understand why anyone cares about what other people do. As long as companies have a market to fill, manufacturers will build phones for this segment. One other thing I notice is that people are people are changing how they use their phone. In 2005, I did everything on my phone ... edited documents and spreadsheets, answered emails, you name it. By 2010, no longer touched documents .... not that the phone couldn't do it... I was simply inefficient, the small screen the thumb typing, was an inefficient use of time. When on the road, It was faster to pop up to my hotel room and open the lappie then sit their thumb typing. I still answered emails, but only if they were a one sentence necessary type. Now I don't even enable email on the phone. I'm never more than 2 -3 hours from opening the lappie and I can be so much more efficient there.