I have to disagree with you a little bit there. The NBA is not traditionally a "defense" league. I know a lot of people grew on NBA ball in the 90's, but in the decades prior to that offense ruled.
Defensive statistics today are given greater emphasis than 50 years ago. Back then, there weren't official stats for blocks and steals. Now, these are 2 of the more glamorous statistics. How many times per game do we hear Mike Breen talk about how Rondo's set a Celtics record for steals, or how he & Kobe are 1st team all-defense?
Detoit's "Bad Boys" of ~ 20 years ago really got the ball rolling with thuggish defense, followed by NY, Miami. This was aided & abetted by so many new players coming in to the league who wanted to play isolation basketball; everyone was trying to be Jordan. So not only was defense tough & physical, but offense got stagnant. At this point, few players could hit mid-range jumpers. The league tried to increase scoring by moving in the 3 pt line, but that backfired and simply created more congestion because 3 pt shooters were no longer far away enough to space the floor, and the resultant congestion actually helped the defense; it was one less step for a defender to run at the 3 pt shooter.
So the NBA eventually moved the 3 pt line back to it's current distance. Since then, a few interesting defensive adjustments occurred: the NBA started really cracking down on hand-checking; the "restricted area" around the hoop was established; and zone defenses were allowed.
Another thing to think about: NBA courts are too small. The current 94' x 50' dimensions were established when players were shorter, weaker, slower. The court needs to be enlarged, and the baskets raised, in order to return the league to it's original proportions.