simple answer: because soon TV (yt) will be 4k and monitors too so using the same resolution is nice and will come in handy for more productivity work.
Having seen the S7 now I think it looks more elegant but not as feature rich
The human eye can barely distinguish between 1080p and 2K. You don't need it. Nobody needs it, unless you're just wanting your battery to die that much quicker because that would definitely happen.