Although there isn't any magic yet in DF, what if the level of of magic in a world can be changed?
I mean that during world building, the levels of magic can be changed from none to high and from rare to frequent. similar to changing the amount of megabeasts and mineral frequency in current DF
For example In a low magic world, the most a mage can do will be to conjure a block of ice, pick it up, and hurl it at a goblin causing the goblin's lower jaw to sail off in an arc. In a high magic world a mage can call thunders to strike down ravens and summon demonic cows to impale bogeymen. A world with no magic will use good old fashioned magma pits or dismemberment.
For frequency, in a world where magic is rare, master wizards are the only people that will use magic and they live in secluded towers like necromancers possibly taking apprentices that become masters themselves as the world progresses and teach others to prevent the magic art from becoming permanently lost. Meanwhile, in a world where magic is common, entire academies are devoted to teaching people magic with the result that even that kobold thief your legendary weaponsmith encountered out in the wilderness can conjure a flying giant sponge.
This can probably create an interesting combination of worlds where magic is used for everyday purposes like cooking (low magic, high frequency), where magic is rare and powerful (high magic, low frequency), or where everyone you see in the game can bend realities to their will without anyone batting an eye (high magic, high frequency).