Well, I don't think he's evil actually anymore so than anyone else.
He is egotistical but not necessarily in regard to the death of his daughter.
I think a lot of us feel bad at the loss of s loved one, not because of Their suffering but because We miss them. Ziyal didn't really suffer that much, it was over for her pretty quickly .
I think Dukat had s lot of issues but he was not pure evil. That would make for an extremely shallow and boring character to have to watch every week on TV.
I don't think Dukat started out as "pure evil" and I found his character fascinating initially. Here was the leader of a once conquering army being relegated to spectator or worse. He was a mixed character having done good things and bad things. He did improve and save the lives of many Bajorans but he took advantage of the situation for personal gain. That shows two sides of his character and there was real opportunity to develop this. Instead they went down the "mustache twirling villain" angle.
DS9 was a well written show but Dukat's character, IMHO, was the weakest link.