Why is Roleplaying important? Well, Dungeons and Dragons is an RPG; you are engaging in a Role Playing Game. If we get real literal here for a second, you are Playing a Role. So much of the fun of playing the game is going to come from understanding and executing the role to the best of your ability.
What is a Role? There are two definitions that I could find, and I think they both apply to DnD pretty nicely. The first definition really feeds into the mechanical aspect of DnD and is something that we understand pretty readily: the function or part played by a person or thing in a given situation. Cool. Are you the healer? Or the thief? Or the tank? Or the spellcaster? What is your Role in the party? But this is just the first layer of your character, the archetype. We want to go deeper.
The second definition is the one I really want to focus on. A Role is an actor’s part in a play, movie, etc. You are an Actor! And you are playing the role of a Character! And, what is most amazing, the script isn’t written for you. You are the one who gets to decide who you want to be! But that freedom leaves you with responsibility, to your Dungeon Master, to the other members of your party, and most of all, to yourself.
This responsibility is one of investment. The more time, attention, and imagination you devote to the creation of your character, the better you and your character are going to be and the more fun you are going to have. This applies not only to understanding the mechanical minutiae and technical aspects of your character (How do my spells work? How can I best employ my class features in combat? How does an attack roll/saving throw/skill check work?), but also the Story of your character. Remember the second definition of Role: an actor’s part in a play. You have one role, your fellow PC’s each have a role, and your DM has a role in creating play, and a Play is a Story.
“Story, Shmory,” you say, “I don’t want to have to think about my character, I just want to hit stuff.” Well then, maybe you should just go play WOW, by yourself, in your room, Alone. Nobody wants to play with a dullard who can’t be bothered to put a little effort in. Besides, you want to tell a titillating story, right? Why play Captain Boring, a two-dimensional, sword-and-shield fighter when you could be Lance Halbrick, disgraced Knight of the Green Palace, forced to flee from his homeland after being blamed for the assassination of the Queen!?
Another thing. Nobody, not even you, really cares if Captain Boring dies. Meh, you can just roll up another two-dimensional fighter. Maybe he’ll swing around a greatsword this time. But for Lance Halbrick to die in infamy before being able to redeem himself and reclaim his honor?! There are some stakes! How tragic if he dies in combat! How euphoric if he wins the day!
When it comes right down to it, DnD is a game of choices. Choices are how you make your personal stamp on the direction of the story. Do I cast my fireball, potentially hurting our tank who is in the thick of combat, or do I delay and potentially get smacked by the ogre bearing down on me? Do we ambush this guy now and try to take him alive and question him, or do we follow him to the baddy’s lair and risk losing him/discovery? What choices you make are ultimately defined by the alchemical mixture of your character and the circumstances that you find yourself in. Now, the circumstances are going to take care of themselves, but it is up to you to decide what to do. And remember, as much as choices and their consequences are about What you do, they are also about Why you do. The more you know about your character, the more engaged you will be in decision making at the table.
Oh no! The party is surrounded by wood elves and they demand that you lower your weapons. Captain Boring and Lance Halbrick are both going to hold on to their swords, but for very different reasons. Captian Boring does it because he sees combat coming and wants some more XP, but Lance Halbrick has a deep distrust of elves from a childhood raid that slew his parents, and would rather lay down his life than surrender to such scum. They both take identical action, but which choice is more interesting?
So, do you see why Roleplaying is important? It is at the core of what makes this game so dynamic and wonderful. Knowing your character, investing your imagination in making them full and complete allows you to make dramatic, motivated choices at the table that make the story you tell with your friends complex and interesting. Go out there and kick some ass!