What exactly is the confusion about role-playing?
Early on in the hobby, there was a terrible mis-supposition. Because the game involved fictional people, people looked for ways to more accurately simulate the whole of their lives. It doesn't matter where your character sleeps for the night, or what his home life is like, or what he did for 3 hours on Tuesday night on Zeno Rising 4 (remind me to post my calendar sometime), because that is not what the game is about!
"What is every last thing Fred does in the 2 weeks till the next adventure"
A maxim of game design is, additional realism hardly ever equates to an equal addition of fun.
Somewhere along the line, people forgot that they were playing a game with certain well defined limits. First a dungeon, then a wilderness hex.
It's easy to understand how this happened. People took the term Role-playing and interpreted it literally, as in taking a role-as an actor would. Instead of what it actually meant.
What would you do in this dangerous dungeon situation? Run? Flee? Will you pull the lever or not?
The role you play is yourself - what choice would you make?
Now it is certainly possible to play from the other mindset, (i.e. "I am Throg of the mountain clans") but all too often, during play, we do not make decisions as Throg would. We end up just role-playing in the sense of the original term - as ourselves. And this is where the difficulty lies, and problems begin.
Do you have to justify the fact that you are a thimble staying in a hotel? Why not? Then why do you feel compelled to justify your reasoning for taking a feat, or a class level?
(Of course there is a lot of worth in the other style of play - but it is often inconsistent (i.e. I'm only Throg when it's convenient) or used as an excuse to disrupt play, because that specifically is what the player is looking to do.
My point is just, when you are having an out of character discussion on what to do next in the dungeon - that is role playing.)