Looking at lists of the highest grossing films of the year, in the last 10 years nearly everything is a franchise spectacle, an animated family film (which has its own category), or a live action Disney movie inspired by their previous animated features. Applying those categories strictly you get a few exceptions like hard sci-fi spectacles that were presumably never intended to generate a franchise (Interstellar, The Martian, Gravity), a musical or two (Mamma Mia for sure and maybe I missed something else), and the Hangover movies.
The winner wouldn't automatically have to come from the top 10 grossing films but I'd think the top grossing movies would have to be a good indicator of "popular film" as it's own category, wouldn't they? And once you start looking at longer lists you mostly find 1) more of the same, 2) the kind of stuff that actually wins best picture, 3) a few more comedies and 4) crap like 50 Shades of Grey that can't possibly be what they're hoping to give this award to (or can it?).