Auras of Danger, Floor Spacing and Shot Creation
One analogy I've recently seen is to baseball relievers, and I think that's instructive if not quite perfect. Some guys (KOJI!) can be pantheon level one year after never approaching that level before and not repeating it after. But Mariano Rivera was for ever. As with Shane Battier and Bruce Bowen - two guys who not only were inarguably plus defenders but also fairly consistent shooters over their careers (at least before Battier's body fell apart the last two years. Guarding the David Wests of the world is doing him no favors on that front). So now teams are throwing multi-year guaranteed money at MLE levels at Danny Green, Martell Webster, Chris Copeland, etc. Green has struggled out of the gate this year, and lost minutes to Marco Belinelli (who is shooting the ball great so far, MoML); Webster has been supplanted by Trevor Ariza who is shooting the hell out of the ball (this year); Copeland can't get off the bench in Indy despite their DESPERATE need for another wing player. Two years ago, it was Dorrell Wright, and in years before that it's been Anthony Morrow, Rasual Butler, and Ariza (again) among others. This year-to-year variation (combined with the difficulty in both assessing and predicting individual defensive contributions) make longer term contracts for these guys inherently risky.
However, while individual proponents of the "3&D" role might have become overrated and/or overpaid, the value of shooting, floor spacing, needing to be guarded sometimes gets lost in the shuffle. This happens even though we recognize and are reminded of it's importance regularly. The Grizzlies have a lower ceiling than their defense and interior talent would suggest because they start one guy who can space the floor. This Pistons have been significantly better on offense when either Josh Smith or Greg Monroe shares the floor with Andre Drummond than when both do (neat sight for checking lineup combos here). On the individual level, players like Luc Richard Mbah a Moute can't get on the floor because the value they bring on defense is arguably eclipsed by the value their (lack of ) offense takes away on the other end.
This does not mean Smith, Drummond or Monroe are not or cannot be positive offensive players. But since none of them need to be guarded outside of the paint, the three of them on the floor produce negative synergy. Replace Smith in that corner with Korver, or even someone who at least needs to be respected like Kentavious Caldwell-Pope, and all of a sudden plays are there to be made: