This is a LOOOOOOOOONG post, but I think the payoff is worth it.
It's useful to look at how the combat roles came about as a comparison.
Every D&D combat, in any edition, is, essentially, about which side takes more points from the other side. Each round is spent taking points, and the first one to 0 points looses. The "survivor" wins. The basic idea of noncombat roles takes this task resolution system, and applies it to things other than killing goblins.
In this very skeletal setup, there's two basic purposes.
Attack: Take points from the enemy, or make it easier to take points from the enemy.
Defense: Prevent points from being taken, or give your team more points.
You could even reduce it further: every combat is about damage and healing and nothing else.
Other than these two purposes, everything else is
intentional design. In 4e, Defenders prevent points from being taken, Strikers take points from the enemy, Leaders give your team more points and make it easier to take points from the enemy, and Controllers make it easier to take points from the enemy, and harder for the enemy to take points from you.
Every other feature of these roles is unnecessary, but probably fun, design. They fit archetypes and make combat more varied and, thus, more interesting. But they aren't essential by a long shot.
So with the same distant eye, we look at noncombat encounters.
Noncombat in D&D has, historically, been very binary. There is success, and there is failure, and the thing that determines the difference between them is the player's skill, maybe your Charisma score, and perhaps a d20 roll.
In order to make "noncombat roles" (and noncombat challenges in general) a possibility, let's keep taking pages from combat, and applying them to other scenarios.
We turn noncombat into a points system. Success or failure becomes about which side looses all their points first, just like in combat. On one side, you have the party. On the other side, you have the challenge (exploring the dungeon or performing well at the king's banquet, or whatever).
Once you have the challenge with points attributed to it, you have the same binary roles that combat has: one side to take points away (and make it easier to take points away), the other side to give points back (and to make it harder to take points away).
If the "challenge" looses all its points before the party does, the challenge is overcome. Along the way, the challenge can make "attacks" (things that make it less likely for you to succeed, like Artillery and Brutes add variety to combat). If you are trained in a particular relevant skill, it'll be like a proficiency bonus (everyone gets 1/2 level, after all).
To mimic the variety of combat, however, let's make four roles, and, to keep it simple, let's have two "attack" roles and two "defense" roles. Let's say...
Role #1: Takes points away from the challenge
Role #2: Makes it easier to take points away from the challenge (increasing allies' attack or weakening the challenge's defenses)
Role #3: Gives points to the party
Role #4: Makes it harder for the challenge to take points away from the party (increasing allies' defense or weakening the challenge's attack).
If the challenge is Dungeon Exploration, it has a DC and it has Challenge Points (instead of Hit Points). Once you remove all its challenge points, you gain whatever goal it stood between you and. It also has the ability to take HP from each member of your party, using things like traps or mazes or cliffs or even monsters, so that if you fail, it kills you. Obviously you can't escape in the middle of it (just like combat!) because the dungeon changes as you go through it (you knock down walls or disturb tombs and it also makes it hard for you to escape).
Role #1 can be described as finding the right path and moving deeper into the dungeon directly. Call him the "Scout." He gets per-day powers like LIGHT STEP that let him move through treacherous terrain, and per-challenge powers like KEEN SENSES that warn him of what's up ahead because of his great eyesight or ear for echoes.
Role #2 can be described as disabling traps, or finding secret passages. Call her the "Infiltrator." She gets per-day powers like FREE PASS that allows her party (and only her party) to pass by a trap without triggering it, and per-challenge powers like PICK THE LOCK that allow her to get through otherwise impassible doors.
Role #3 can be described as finding food or allies in the dungeon and repairing the wear and tear on the party. Call her the "Survivalist." She gets per-day powers like COOK ANYTHING that allows her to keep her party fed, and per-challenge powers like EMERGENCY REPAIRS that allow her to jury-rig damaged equipment in the heat of the moment.
Role #4 can be described as learning about the dungeon beforehand, puzzling out the answers to its most difficult riddles and perhaps gaining a map. Call him the "Explorer." He gets per-day powers like I'VE HEARD THE TALES that allow him to prepare the party for the vicious undead that lurk within its halls. He gets per-challenge powers like TURN LEFT HERE that let him cut through the illusory wall that the tricksy faerie have put there.
For any other challenge, you can pretty much change the names and some of the effects of the powers to accommodate it. After all, this is the same basic resolution that works so well in combat, and all this is is
detailed task resolution.
Let's do a quick social encounter scenario? Anything from a gala ball to an election. It has a DC and Challenge Points and let's say the PC's have some sort of "social HP" (reputation?) that they can loose. Failure might not mean death here, but instead means that they look like idiots, their ploy is obvious, and people will think they are evil mountebanks with nothing but their own black hearts to care about. The social encounter attacks you with things like Character Assassins and Grumpy Royals and Over-Affectionate Sychophants.
Role #1 = Alpha. Very charming, likes to talk others into giving her what she wants. Powers like DISARMING BEAUTY that make social encounter want to help you and OUTRIGHT PANDERING that makes the social encounter feel like you are one of it...
Role #2 = Mudslinger. Makes everyone else look worse. Powers like UNFORTUNATE INCIDENT that arouse suspicions about the morals of one of your enemies here, and like OUT OF CONTEXT which casts aspersions to distract one of your threats.
Role #3 = Spin Doctor. Covers up the dirty secrets and black marks on the record. Powers like CHANGE OF TOPIC that helps recover from a slip of the tongue, and like CONVENIENT MEMORY that let them avoid social attacks by pleading ignorance.
Role #4 = Wingman. Makes the party look good, knows all the right connections, has done his "homework" on these guys. Powers like OF COURSE YOU'VE HEARD OF US that makes the party very impressive and YOU'RE VERY LUCKY TO HAVE US HERE that makes the enemy feel weaker.
With enough pagecount, I could entirely go to town on this system. If I wanted to give this in the core of 4e, with everything else in-tact, I would dedicate the portion of the DMG that talked about skill challenges to instead talking about this way of looking at challenges, these four roles, and some examples. If I had my druthers and could allocate 4e as I saw fit, well, let's just say I'd be cutting or simplifying enough in general so that pagecount wouldn't be a concern.
Think of something like a hypothetical bard. In combat, maybe she is an Arcane Leader. In the dungeon (or wilderness), she's an Explorer. In dealing with the royals at the banquet, she's the Alpha. When solving a mystery, perhaps she is the Interviewer (which is Role 3, giving you more points; Role 1 is the Investigator, taking points from the mystery; Role 2 is the Analyst, making it easier to solve the mystery; Role 4 is the Hassle, which gives you more time to solve the mystery and makes it harder to cover up)
Crafting probably wouldn't benefit from the "Roles" system because there's not so much a direct challenge to overcome (well, building the item, maybe, but generally the appeal of crafting isn't so much the building of the item as it is the use of the item later for some other end and the feeling of self-sufficiency...crafting something isn't a challenge, but it can be an important character asset).
But where the point is "to overcome some obstacle," combat mechanics can be a useful metaphor for it, and the roles can add a lot of variety to it.
There. It's rough and tumble, but give me 10,000 words and a publishing contract and I could probably do more, better.
Non-combat roles are a workable idea. Those four roles are in *EVERYTHING* that is anything like any edition of D&D's combat. Any task resolution where the first one to 0 looses has these roles in them. You just have to want it. I'm not altogether sure it's the *best* idea, necessarily, but the idea of "making noncombat another form of combat" has, at its core, the intent to give support to dramatic, pitched, varied, and interesting interactions that don't necessarily involve stabbing goblins by using combat as a metaphor for task resolution.
To come out the other side of this, I could reduce combat to a single attack roll the way that negotiations are boiled down to a single Persuasion roll, if I didn't have much fun in combat. These things are already on the same continuum, this is really just about bringing them closer together. Which, admittedly, in D&D, has been very, very taboo since 1e. The wrought iron fence made of tigers between RP and combat was drawn long ago, and I guess I'm just sad we haven't been able to get past it in 4 editions (and extra sad that 4e stepped away from 3e's attempts to get past it, rather than taking them further).
With regards to making archetypes, that's where something like a Profession system could come into play, if you didn't want to link it to class.
So you can have some sort of Aristocrat class, with a combat role and an Exploration role and whatnot. Or you can have an Aristocrat profession that gives you certain noncombat roles (and access to those powers).
