Seems
no one really knows why it's 82 games. Well, we know that it was extended from the 80 games teams played during the 1962 season to 81 in the 1967 season, and then from 81 to 82 games in the 1968 season when the San Diego Rockets and Seattle SuperSonics joined the league. How it got that high in the first place though, no one really knows.
As that article from 2011 that I linked to notes, it comes down to tradition more than anything else. Your mileage may vary as to whether that's a valid reason; oftentimes though, "that's the way we've always done it" isn't a compelling argument. Revenue is obviously a factor in keeping the current length, of course. However, I do think that a longer season does allow for more ups and downs, more opportunities for teams to rise and fall.
The possibility of injury is often cited as a reason to shorten the season, but by the same token, an unfortunate injury early on in the season needn't scupper a team's chances when there's 82 games to play. In other words, if a star on a contender rolls an ankle and misses a couple of weeks early on in the year, there's plenty of time for them to return and the team to recover. It also means that players aren't compelled to rush back too quickly from such injuries because the team needs them, potentially making their injury worse; there's time to turn things around, so they can and should be patient.
It's also why I'm not a fan of the Play-In Tournament. If you can't make the top eight in the Conference after 82 games, you shouldn't be in the postseason. I also dislike how the 7th and 8th place teams are punished for not finishing better, but the 9th and 10th place teams are rewarded by finishing even worse with an extra chance to make the Playoffs. But that's getting into another debate entirely.
I think there's definitely an argument for shortening the season. The discombobulation of the lockout aside, the 50-game 1999 season was exciting because it was still long enough to be a rollercoaster, yet short enough that teams couldn't afford long losing streaks. The same goes for the 66-game season in 2012. However, with the revenue that the league, teams, and players would be giving up, I don't think it's very likely.
Personally, I feel it's fine as is. My inner Grumpy Elder Millennial feels like shaking his fist and muttering about short attention spans these days, because it felt like we all used to love the ups and downs of the regular season, followed by four rounds of the postseason. It meant NBA basketball close to all year round. We also used to see far more players playing in every game thirty years ago, and non-contact injuries weren't as prevalent either. At the same time, I'll admit that the main explanation is "tradition", so it's not an integral aspect of the game or based on any kind of formula (like, say, the 24-second shot clock). Once again though, the revenue they'd leave on the table suggests that the season won't be shortened outside of extenuating circumstances like a lockout (or pandemic shutdown).