Good can be Malevolent and Evil can be Benovolent.
So if we have beneficial good lands, we will need beneficial evil lands.
Good and Evil region are called Good and Evil, because they represent the childish cartoonish concepts of Good and Evil that feather-like grass and unicorns are Good, because they look cute, while actually Good and Evil are just debatable philosophical concepts.
Goody-goodish hippie-style place can be a real nightmare to live in, especially if your freedom of actions is rather restricted. So, Malevolent Good should be a place, that is hospitable enough, but only until you start committing acts, deemed by Good region inhabitants as inexcusably evil - like slaughtering animals or cutting down trees. Then the inhabitants would repel against you. So as long as you follow rather strict set of rules - you are tolerated there.
Sort of like Garden of Eden from Bible - you take a wrong fruit from a wrong tree - and you are suddenly not welcome anymore.
In Benevolent Good region the creatures would be simply too scared of you to attack or too weak to cause you any serious harm, so that you can live there without having constant danger of your fortress being destroyed.
Benevolent Evil would be place that looks rather undangerous for you to survive, but it insensibly constantly affects your dwarves, like slowly changing their personality traits into more evil ones (less compassionate, more prone to anger, etc.) and eventually changing ethics of your dwarves, making the fortress separate from its civilization and start its own.