ExploderWizard
Hero
They're already getting less out of the game by not paying attention, simply because they're not paying attention. (Much like I'm devaluing my movie ticket if I look at my phone the entire time the movie is playing.) It doesn't necessarily follow that their outcomes should be worse if they aren't paying attention. It depends more on if it's a priority to test player aptitude at paying attention to environmental details as a function of play. I, personally, find those details to be a distraction for the sort of tabletop play I'm looking for, but that's ultimately a personal preference.
The game is for the player, not the character. As a player, if the effort I'm putting forth to engage with the game doesn't have an impact on play then the game isn't worth playing. The best way to keep everyone engaged is to make sure that it matters.