IMO a big structural problem in adventure mode is that the only way to get your skills to the level you need to access content like kill big monsters etc is a) a boring repetitive grind b) involves murdering large amounts of innocent beings.
The grind is fun for a while, but it gets old to have to abuse animals on each new adventurer. And it to me is bad for roleplay - I feel more like I am playing "Animal abuser manager" than an adventure game.
This incidentally is a problem is many RPG games has - it stems fom the old D & D concept of getting xp every time you killed a monster. In games it easily becomes boring grind and senseless killing in order to get the XP to unlock mid and end game thing - but I know a concept from a game that fixes this.
EXCURSE;
It's an ancient Japanese game called "Princess Maker" from like 1999. I highly recommend the devs to try it out, as it has a really cool character building system. The game IS building a character - you control a girl from like 15 year olds to 20, your choices affect what the ends up as being at 20. I never managed to become a princess, but I remember stuff like dragon slayer, housewife, diplomat, gogo dancer, assassin.
XP there is gotten by jobs - all job gives you xp in some skill, removes xp in other skills and pays you money. So like lumberjack, you get xp for strenght and endurane, loose from intelligence and reading.
And this makes it hard to balance your path so your character doesn't become like a hulk like super strong moron or a frail scholal, but you end up with a character that is both strong and bookish.
BACK TO DF:
In DF Adv mode this could be implemented by adding that the character could take jobs from NPC. Like you talk to the local hunter and asks him to work for him, he says ok, you hit ok, then you get the "time passes screen" you have when you sleep or wait, and when it's done you have some archery and ambusher xp, the same xp dwarves get from the jobs in Fort Mode plus some money. 10 clicks or so and you're legendary and you've been a hunter for a good while.
Jobs you should also have some downsides. Like a hunter job removes xp from other skills. If you only get positives it also becomes a grind. It could be that jobs lower other attributes. So say fish cleaner increases Agility, Endurance, Kinesthetic Sense BUT it decreases empathy, intuition and language or whatever. That way, you'd have to carefullty choose a path to get to where you want to, and not be like a strong brute or a very agile disease prone weakling.
Eventually all the labors from fortress mode should be available. So you could get a job as animal caretaker, and it would train the attributes Agility Analytical Ability Memory Empathy. (The wiki says it trains those attributes.) People would more be interested in job that trained combat skills like hunter, guard and such. And strength and endurance, like woodcutter.
It would make developing your character much more fun and roleplayish. Instead of walking around and breaking the legs of impalas and beating them into a pulp, you'd be looking for job positions in the various sites. Along the way you'd develop organic relationships with NPCs, like the old elven hunter you worked for for your throwing/archer.
Combat skills
Should be trainable as working as a guard in sites OR by paying for classes to a martial arts teacher, and those should be hermits living on top of mountains or something like this. And they should refuse to train you a lot of times before they accept you.
I find it very non RP that you learn combat skills by assault and murder, behaving like a serial killer - it's better the way they learn in fortress mode, by training and sparring. If you wanted to do martial arts IRL, you would not go out and assault wildlife
They also didn't in the middle ages, they trained in a gym.