First of all, there's regular black licorice and salmiakki/salmiac aka salty licorice; in Finland/Nordics these are two separate things. We have four categories for candy: licorice, chocolate, salmiakki and fruit/others.
It was only few years back that I found out that salmiakki is in English called salty licorice and that (practically) all salmiakki candies actually have licorice in them. I had always thought of them as two completely different things.
I mostly eat filled licorice - our three classics are chocolate, mint and (mild) salmiakki flavored fillings, I don't like fruit/berry fillings - but straight up black is fine too.
But salty licorice is the true Nordic delight. Whether it's the Danish style ashtray flavor or Swedish piece of pure salt or the more sophisticated Finnish kind, with hints of sweetness and mint among the basic bottom-of-garbage-can salmiakki taste, all salty licorice is food of gods for me.
May have been years that I've had something salmiakki flavored every single day, mainly due chewing gum.
Fun facts: the Finnish name "salmiakki" comes from "sal ammoniac", "salt of Amon", a name for the flavoring salt ammonium chloride. The substance was supposedly found near ancient temple of Amon, though the medieval authors may have mistaken.
So far as why, I'm going to guess it comes from the wide variety of foods I ate when I was young. My parents always insisted we at least TRY something new when it was presented to us. We didn't have to eat it all, but we would at least have to taste it. From that, I like things like fennel, or anise seed items (rye bread, Italian sausage, etc.). Which then leads to black licorice which is a very similar taste, but sweet.
Now my wife can't stand black licorice, fennel or anise. In general she was brought up on foods with less seasoning/spices in them. And was never required to taste new foods when she was a kid.