If folks are interested in a discussion of the pros and cons of having rules to support your RP instead of letting your RP be diceless, I will unashamedly pimp the two latest episodes of Return to Northmoor, wherein we discuss exactly that at length.
Here’s a quick summary though: You absolutely do not need rules to role-play. D&D has gotten by for 30+ years with a diceless RP mechanic. So, why introduce rules for that purpose?
1) You would like the rules to help you break out of RP ruts that your group may fall into through long-time play.
2) You would like to increase the engagement of tactically-focused players in “pure RP” scenes in your game.
3) You would like to increase and maintain the focus of your RP scenes on the characters, and not the players.
4) You would like the rules to encourage and reward your characters for taking RP risks as well as combat risks.
Just some thoughts…