My lifestyle and use of my phones don't require a screen protector. They've all been it excellent condition when I hand them down
For some people who drop their phone yes they certainly need screen protectors.
I would say that screen protectors do very little for people who drop their phones. The tempered glass protectors offer slight protection, but the plastic films will do next to nothing for drops. These screen protectors are for protecting against scratches from more innocent things such as putting your phone in your pocket.
Depends on the phone and how much your willing to spend to protect it. Overall, your phone should last a lifetime without a screen protector.