these are some of the most fit athletes in the world...and during their off time in between seasons theyre still playing ball and working out (if theyre not partying)
do you really feel bad that they have play 32 minutes of basketball 2 nights in a row?
It's not about feeling bad.
If you play ball one day, you're not going to be 100% the next day.
It's usually pretty visible, guys aren't moving as well as the did the night before. Also, most players numbers go down on the 2nd night, except for the young guys.
Not to mention who wants to see star players sidelined with injuries weeks at a time? That can be reduced with fewer back to backs.