L/D IS important especially if you operate from a field where nearby
landings are hazardous. Students ( and for that matter some instructors)
aren't good at judging just how far they can glide. In this situation,
extra performance is what gets them home after a mis-judgement.

An instructor who cannot reliably judging his glide range should
immediately have pulled his instructor license. I don't know about the
place where you fly, but where I do, no student will be sent to his
check ride before he has demonstrated that he masters the calculations
in flight. Extra performance doesn't add any safety, it just shifts the
numbers in the calculations.