Now that you mention Monomyth i remember an old idea of mine. To break mundaneness, we can have a hidden parameter with value increasing overtime that effects random encounter formulas increasing their probability. If a player keeps chopping wood that value increases chance of a bandit raid to his little town. When player completes the encounter he id given a choice to return his chores and reduce that value or pursue a new adventure and increase the value for greater encounters and rewards. But lets not drift away from the main topic. I agree this is a good topic. Lots of good ideas...
Well questing/adventuring is a broad definition. While it mostly refers to get quest, do task, get back for reward type of structure, i also consider rescuing random prisoner from imperials, or chopping wood in local lumberjack for money in Skyrim a quest. It is up to content designer to create these seamless experiences.
Returning to using rules part of questing mechanic, you can think of a thieving role where you receive no quests but as you steal your thieving levels up you can now get access to quality fences informants etc. Or you can level up in Bandit role can hire shady characters as guards etc. If you can provide a system where resources for these roles do not deplete ( like fishing ) player can continue to steal or raid camps as long as he wants.
This discussion has steered in a certain way so i don't know if what i am going to suggest will contradict with previous posts.
When i read about classes and roles, i immediately thougth they would be connected to distinct game mechanics. You can leave robust class system with everything balanced out as part of combat system, and make roles part of other game mechanic.
For example you can make use of roles as part of questing/adventuring in such way that roles unlock and level up via doing related quests. Passively effecting combat system with rewards, skill unlocks etc.
Or use roles much like professions, a money making/item building mechanic.
May be you can implement a synergy system where your friend's influence on faction standing is weighted by amount of "playing together". So you would be more synergized with friends you play with rather than people you just added as friends.
"Playing together" can be defined very differently. Here are some metrics to calculate that:
Being in the same guild. ( a small instant boost )
Finishing a quest together
Finishing a raid together
Trading ( may be exploited so it should have a upper limit )
Forum participation ? ( May be you can implement a system that is connected to community forums)
Maybe if game incorporates some systems using the player names, players may digest the predefined name list concept easier. For example if you can trigger a quest reward if you have a "Barbaric Surname". Or if you can create lineages like guilds and carry some reputation with your surname. Of course if you are going to go with a predefined name list you will definitely need a Gamer ID