Because it's not a panacea to all problems, and it requires practice time, which is a finite resource. Here's some other things I wish Cal would spend more time on (if time was unlimited): out of bounds plays, swing offense, pick and roll D, 3/4 court trapping, FTs, 3 point shooting, boxing out, dribbling, beating a press, pick and roll O, jump balls, Oklahoma drills, weight lifting, and coordinated bench cheers (have you seen Monmouth's bench?).
Guys, we lost our starting PG (twin1), SG (twin2), SF (Lyles), PF (WCS), C (Towns), backup C (Dakari), and backup SG (Booker) to the NBA. Returning are our backup PG (Ulis), injured SF (Poy), backup PF (Lee), third string PG (Hawkins), and 4th string PF (Willis). And people here insist that if we just spent the practice time on learning multiple defenses, we'd be 1) good enough with both that we'd be good, and 2) there would be no resulting decrease in other areas. That's a pretty hefty assumption, because last I checked a zone requires coordination between teammates and an awareness of how to play zone. It's not a 5 minutes in practice thing.
Guys, we lost our starting PG (twin1), SG (twin2), SF (Lyles), PF (WCS), C (Towns), backup C (Dakari), and backup SG (Booker) to the NBA. Returning are our backup PG (Ulis), injured SF (Poy), backup PF (Lee), third string PG (Hawkins), and 4th string PF (Willis). And people here insist that if we just spent the practice time on learning multiple defenses, we'd be 1) good enough with both that we'd be good, and 2) there would be no resulting decrease in other areas. That's a pretty hefty assumption, because last I checked a zone requires coordination between teammates and an awareness of how to play zone. It's not a 5 minutes in practice thing.