I think that's the interesting thing about batman. He's just a dude.

Granted, he has a lot of money, but at the end of the day, he's just a dude, that enjoys solving mysteries. He's a hobbyist detective.

So yeah, all his villains are going to have similar abilities (Later they had the clay guy and croc and people with actual super powers). But the idea was for a guy that just liked solving crime.

And you have to make that memorable and go in on what's vogue at the time - so they made him have this whole bat identity. And ok, that adds an interesting back story, and similarly the villains need to be memorable too, but not super-powered.

So the villains, are some of the most interesting because they can't just do something because their super-powers granted them the ability, they have to actually think and plan and have interesting motives.

And two-face is either an agent of chaos or presldestination. And to my knowledge they never explore that, it's open to your interpretation.

Edit: batman also came out at a time when mental illness was really starting to affect society. Back in the day if you were mentally ill, they just called it evil, and put you to death. But then people started examining stuff like that and say "Hey, we might be able to help these people." So then you have the state-run looney bins which is rich soil for batman-type villains.