Why not mesh them both into one giant Career mode?
Start out as a humble dwarf, heck, as a baby! (childhood should be the fastest stage, to learn more about the starting area and community. Possibly pick activities that would flesh out your initial skills and stats later.)
Once matured, you, as an aspiring member of the community, have to take up a profession. Will you be the errand boy, hauling those stones and building your strength&endurance up, maybe rather help in the kitchen and develop, um, cooking skills. HEck, sod all that and go adventuring at will!
As you progress in life, you develop your esteem among your community or civilization. At one point you may be offered to lead a dwarven expedition to settle a new hamlet. Thus begins the Dwarf Fortress mode. (Of course simply getting a few other dwarves to join you and gather some supplies would also work).
Or you could try the military career, enlisting as a sheriff, broker and bookkeeper for the economic career... Or you could develop your hamlet into a thriving self-sustained town, become the duke of county and found/manage multiple hamlets/towns simply by giving orders to mayors or even micromanaging by attending to the place personally. Grow an army... etc.
The ultimate goal? Why, it could be becoming the new king, pulling strings over the whole kingdom and staging wars against monstrosities and other kingdoms alike!
All seamless.
Awesome? Epic, I say... I am worried about the time span this would take to complete. At the end, the player would be rewarded with an epic story of the life from humble beginnings to glorious (or maybe not so glorious ending) - written as a legend if you've become a hero or king or written as an anecdote that anyone barely remembers or even pays attention to if you wandered into goblin snatcher's dirty hands at the early age.
I suspect that the Toady One already had such an idea from the very beginning...
All joking aside. I wouldn't mind if it was an option, just not mandatory. I'm one of those odd fellows who doesn't like adventuring. Just has a God complex.
Mortal mode compared to god mode. Could become a veteran soldier adept at hacking limbs off, a professional hammerer with the RSI, stoic fisherman with obsession for carps, a dull recordkeeper or go for the big thing: The King, which of course requires the 'god' mode in major part.
How to become the king?
Economic route: Hamlet leader (colony) -> Mayor (town) -> Baron (town + surroundings) -> Duke (county with its several towns and army) -> King (the whole kingdom).
Military route: Axedwarf -> climb ranks up and eventually become a Commander of a dwarven military fortress (don't worry about economy, resources come as long as you ensure their safety) -> military campaigns -> climb a few more ranks -> major campaigns (wars) -> The King!
Or an adventurer mode... Save the world -> become a Hero -> The King adopts you -> King croaks, you get crowned!
The possibilities are numerous - as long as you have an ambition. Of course you could be content governing the hamlet in entire detail (meeting the needs of Kingdom, fending the hostiles off, engaging in a diplomacy with other towns etc.)
Original Dwarf Fortress mode? Just start as a single dwarf, grab a few friends as soon as you can, a couple picks, an axe and go found your own hamlet. Refuse any Baron promotions and it would be the same old Dwarf Fortress mode (of course with extra features such as provincial trading and diplomacy).