We do have a renewed emphasis now on special teams, but we'd also be remiss if we didn't put things in historical context. Kick return numbers are unsurprisingly heavily impacted by recent rule changes but most of those guys you mention are from an era that's very different in terms of punt returns, too. Punters, on average, have gotten much better at ball placement and coaches are more intelligent on when to punt. In the modern game, possession is generally prioritized over field position.
There are teams that just don't see the value in practicing special teams and are content with just gaining possession and getting on with it.