It’s always nice until you drop it without a case on.
I guess I'll learn my lesson if that happens. I'm careful with the phone, and I have AppleCare. However looking at drop tests it seems like the 11 Pro is pretty resistant to most regular drops. Of course I know that in reality those simple drop tests you see on YT don't really matter, since you may drop your phone and something that is even a tiny bit sharp and all of a sudden the pressure (?) of the collision makes the damage 10 times worse. Of course there are tons of other variables as well.
I ruined my SE by using it without a case for an extended period of time (sides of the phone dented easily, ports became filled with dust and stopped working), but if similar things don't happen to the 11 Pro, then I almost see going without a case as a way to utilize the improved durability of the phone, which contributed to the $999 price tag.