It didn't take long after me mentioning Dungeons & Dragons until the first commenter popped up saying that this wasn't the best system to roleplay with. Specifically Inquisitor said: "4e doesn't *stop* you running an actual story, but it really doesn't help you, either". Which brings us back to a debate which is over 30 years old: What is the role of a rule system in a pen & paper roleplaying game?
Basically there are two extreme positions, and lots of shades of grey in between. The two extremes can be called minimalist and maximalist. The minimalist point of view is that the rules only get into the way when roleplaying, thus ideally you'd have as little rules as possible. Rules are there to solve situations that can't be solved by talking, e.g. the old problem of children playing cops and robbers: "Peng, peng, you're dead!" - "No, I'm not, you missed!". While Dungeons & Dragons produced hundreds of rule books, the basic rules of the game have always been on the minimalist side. Thus Inquisitor's comment that these rules "don't help you roleplay". He is right, they aren't designed to. They are rules for a tactical squad based combat game, initially made by a company that shortened it's names from "Tactical Studies Rules" to TSR. The story content between combat is a lot less regulated in D&D, and has far more degrees of liberty. Including the option to not do very much at all, and basically run just a miniature wargame in a fantasy setting.
The other extreme of rule sets, the maximalist one, thinks that the rules should aid and encourage roleplay. To achieve that, they are often a lot more elaborate. Their proponents often praise them at being "more realistic", as far as that makes sense when you are roleplaying a wizard. For example maximalist rule sets don't simply reduce your health by X points when you are damaged, but use tables with hit locations telling you how those X points that landed on your right upper leg is affecting your movement speed. Maximalist rule systems also tend to have more rules on the non-combat interaction between players and non-player characters. If a character wants to haggle over the price of a sword with the NPC merchant, a minimalist Dungeon Master has to invent the reaction of the NPC on the spot; a maximalist Dungeon Master gets "help to roleplay" in form of a table in the rule book where based on a dice roll, some stat, and some skill the exact rebate from the merchant can be calculated.
Personally I much prefer the minimalist approach. Of course it requires a more creative Dungeon Master, but then it gives that creativity a wider range of freedom. The last thing you want your pen & paper campaign to become is an exercise in rules lawyering and endless looking up of tables. Roleplay is better than rollplay, we used to say. But the debate is certainly still alive, and not everybody has the same preferences.