Defenses still matter in the big games when the scoring goes nuts. When you need a stop to win that big game the defense that's been doin it the entire year the best tends to rise to the top.
Also you can see that the proliferation of weapons out of the backfield, and heavy use of screens and short passing game with pulling OL, that the wise teams are going to load up talent at LB. It's been a trend to have speed there, but even moreso now the way the league is trending to a "who has the best redzone" type deal defensively.
And lastly you just cannot have enough cover corners. Those dudes are never gonna go out of vogue.