Today's soccer is considered boring by some of the fans, claiming old games used to be more fun to watch, but you don't see big leagues cutting 90 minutes of game time to 80 just so the fans could go home early.
Your star players getting injured? Be better at team construction and player development so you have a backup plan and don't wear your star players out.
If NBA wants 40 minutes format, this eliminates current gen players from achieving some of NBA records in the future. Plus you may never know and scoring averages could drop down just like it was back in old days from high scoring 80s to low scoring 90s. And then what? Back to 48 min again? This is a gimmicky solution. Reduce ticket prices then. I bet none of them will do that.