Dude, the potential for great plot has always been there, and has been exhibited from early on; RPGs have leaned heavily on plot elements from the get-go. The presentation of stories has changed and evolved, as with any other narrative form, but good plotting is not dependent on hardware or...or time. I'll conceded that strong stories are perhaps more valued in action games than they were two decades back, mind.
"Gameplay" is an extremely broad term; care to narrow it down some?