Thin on the Ground?
Because older games had to make the most of limited floppy disc space, particularly on the Amiga, each location in an adventure was made to work hard for its keep. Each screen was filled with wonderful characters, objects to collect or interact with and hotspots to examine. Now, with the ability to cram ten times (or more) the number of locations onto a CD or DVD, even at very high resolution, the number of interactable items on each screen/location has reduced for the same amount of gameplay. The Interaction Density has decreased drastically, to the point in some places where there are strings of locations through which all the player character does is walk.
Game players of all ages don't simply want to wander around, particularly young kids with notoriously short attention spans, so when there is little to interact with, the natural conclusion to draw is that adventures are boring and not worth bothering with. Action games, in comparison, offer an almost constantly high Interaction Density and are always going to be a better draw to gamers who want to be always "doing stuff" in the games they play.
Clearly, the time has come to address this balance by thinking more creatively about the layout of adventures so that they offer the same level of Interaction Density they used to.