I don't know if I think the gypsy curse was successful in accomplishing its goal of punishment. I do know that I think it goes a long way toward making Angel the champion that he is, though.
That's an interesting thought.
In the Dark Horse limited series "Angel: Long Night's Journey" by Joss, this very thing is addressed.
Angelus was a test subject of re-ensoulment for another vampire in order to make Zheng a champion.
As for Angel/Angelus...
He does know inside that what the vampire becomes is based upon their life as a human and their personality. He states this to Willow in "Dopplegangland".
These inner motivations are unleashed when becoming a vampire.
Angel knows that Angelus is him unleashed. I think his problems come from accepting that fact.
Here's the rub that keeps him up at night (so to speak); Angel knows he will never be as good at being good as he was at being bad.
So yes, he does create a duality in self to cope. I think his brooding is more from keeping this duality in check than reflecting on harm that another "entity" did while possessing his body.
The reality; Liam felt he was belittled and given the paternal doom of amounting to nothing. So he attempted to excel in carousing, a feat mastered by the ne'er do well. When given real power as a vampire, he excelled at that. All to spite his father.
His punishment, a soul and loss of the lust for the kill. Punishment indeed for one such as him. Never again to excel in his chosen profession.
Angel admits several times that he misses the clarity of it all.
The dreams in "Somnambulist"; he admits freely that they're not nightmares and that he
enjoyed them.