Because it's becoming more and more common for people to pay less and less attention to the more intricate aspects of games. That's why the casual games market is expanding and every publisher wants to cater to the Call of Duty type of person who has a short attention span, the kind that skips tutorials just so they can get it over with, talks or texts on their phone instead of watching cutscenes or even worse skipping them all together because they need their gameplay fix immediately, has their game volume on low because they prefer to listen to the latest hot album instead of the game's audio narrative, character chatter, and sound cues...etc.
I remember Joe complaining to other Joe about how he couldn't climb up an unimportant dumpster or cars in QB while the story was unfolding in front of him, cutscene volume drowned out by his moans and cries. Or when Jeff trying to play it as a cover shooter in that famous gif when the game tells you in the first firefight you encounter that cover is only as a temporary stopgap to recharge abilities and heal. It even pauses the game for you to deliver the message if I remember correctly, but people like to insta-mash A to get rid of the prompt and get back to shooting.
How many times have I read on GAF people complaining that games are short when it turns out they just rushed to finish each level instead of paying attention to the environment narrative, skipping cutscenes, then complaining the story sucked and the game was short when they paid jack shit attention.
People not playing games properly is a real issue that exists. The attention afforded to games is diminishing all because they need that quick fix of action.