This is a very limited example. I've worked a couple of trade shows where I was showing potential dealers and users the app for viewing pics from cellular trail cameras. Even a large phone is a bit small for showing the app and photos to people. An 8" tablet is just about perfect. Everything is large enough to see but you don't get tired toting it around the booth all day. A larger device (e.g., 10" or more) is just plain awkward to use all day in a situation like that.
Tasks that require good visibility but don't require a ton of typing (just finger input) often work well on the 8" size and that will fit in large pockets, where a larger device won't.
Exactly, and working in the field, I'd prefer to have something that I can have both hands free when I need, but still a screen big enough to see if I have to put it down.. My 8+ isn't quite there.. And there are some apps/features that a iPad has that an iPhone doesn't..
WHERE IS MY IPAD MINI PRO? =(