So what's actually happening here why is it that the number of large screen smartphones being sold are actually increasing that who would actually ever need a phone that big so I haven't seen anyone give their opinion to why that so I'll give it a shot.
We are talking about the phone tablet trend at first there was some major misconceptions about the form Factor people said that the tablet phones are useless they weren't phones and they weren't tablets there were somewhere in the middle and nobody would use them it was going to fail, the same people now seem to be surprised that the form factor is selling so well and many phones are starting to get bigger because of it as it will be discussed here the reasoning behind it is actually pretty simple with a bit of logic it's easy to see why people are buying offensively oversized phones there's a simple formula that acts like a bit of a rule of thumb for this kind of thing it is " value= benefits/cost " a phablet phone traditionally dont cost that much more than a regular phone if it all but with this being said you get much more benefits because of the larger screen size obviously that's just more value 
from the get-go of course there are two sides to this it depends on the individual user so the people who will benefit most are the people that use their phone for everything with a phone tablet they get much more screen real estate ,texting is easier, browsing is easier , gaming is better , movie watching is better and depending on the phone you can even get some Multitasking and specialized features you get the point the bottom line is and I think you will agree with me that screen is the central component of a smartphone so more of it is definitely welcome from the functionality standpoint so overall for this kind of use of the only negative point would be the physical size in the terms of pocketiblity , now the second side the second kind of user these are the people that will not benefit from the phone tablet , these people don't use their phone for everything and hence its going to be hardly any benefits for these guys but you still have the negative aspect of the physical size of the phone see you get even less value than a person who buys a regular phone so in asense the phonetablet makes very little sense for preson that doesn't use their phone that often now of course opinions are changing and we may see a shift from more of the second category of people towards the first now the natural progression for the attitudes of people who are against large screen phones are as follows:
First they say it's too big ridiculous and just look stupid then if they get to use it for 2 or 3 weeks they find that it takes a bit of getting used to and then after this they tend to enjoy the benefits and as a side effect they may start using their tablet a bit less this is exactly what we started to see last year with many of the new adopters of the new LG G Series and now this is being officially made mainstream with the iPhone 6 Plus however Apple failed to fully capitalize on the form factor in terms of software features so what's the cognitive reason for sacrificing physical convenience for a bigger screen well as many of you know phones are no longer just phones, and you do every task with it and it's with you all the time in fact a recent study showed that we have our phones with us more than 90% of the day so the benefit of just convenience in general the number one reason why people choose to use their phones to browse the web for short periods of time and do other casualties on their phone versus a PC or laptop so given this when we want to make the experience as full-featured and as comfortable as possible without squinting and as we begin to use smartphone for more and more things this is only logical.
So I hope that clears up many things.
