Teams score less now(the little .7 point drop in scoring doesn't prove that teams play better defense now btw)because players aren't as skilled now vs 20 years ago despite being more athletic. This is why the league had to help offenses out by changing the rules. Offensive play has deteriorated over the last 20 years. Teams are taking damn near twice as many 3s nowadays vs 20 years ago. That the influx of HS and one and done kids. Anybody who honestly thinks that teams play better defense now compared to 20 years ago is clueless.
The year before the handcheck rule was put into place the league average was 93.4ppg on .439%, today it is 100.8ppg on .453, that is a substantial difference when we're talking about an entire league. And even with that rule in place we have teams comparable to the best defensive squads 10 years ago, statistically the Pacers are one of the best defensive teams ever, and this year when Gasol is in the lineup the Grizz are also one of the best defenses ever.
So, players aren't as skilled today as they were 20 years ago, yet they shoot a higher percentage on 2pt shots and a higher percentage from the freethrow line? No, the league helped out offenses because teams were starting to take advantage of the zone principles and in conjunction with handchecking and all these SF's with 7"0+ wingspans it made scoring insanely difficult. Look at it like this, 20 years ago John Starks was guarding the best perimeter player on the opposing team, today Paul George gets that assignment. Who would you rather have defending people on the wing, Starks at 6'3" or George at 6'10"?
Teams take a ton of 3s because they have to, not because of a lack of skill, that doesn't even make sense when you stop and think about it. Despite taking twice as many 3s, the league average today is .360% from 3, vs .366% 20 years ago. So, you can't have it both ways, you can't say they are less skilled even though they shoot comparable or higher percentages, especially when you have defensive squads in the league today that are better than any team 20 years ago.