People keep saying that good areas are meant to be easier to survive on but I disagree. Currently there is no difference is survivability between normal areas and good areas, only in tree types, grasses, animals and plants. If these areas are as blessed as they are, they should be highly contested, and the idea of being overly good could work if used in the right way, but would depend on what dwarf fortress can currently do within its inner workings.
For example:
Healing Mists: Yes they heal your dwarfs, but in the same respects they should heal any injured ambushers or seigers. Perhaps healing works by an 'increasing metabolism to heal' premise, so dwarfs heal faster but also suddenly get hungry and thirsty. Maybe even have some creatures that are healed faster in mists than others due to also being good aligned, so a unicorn heals faster in 5 seconds of mist than the dwarf attacking it, which turns the tide of battle and lets him gore Urist to death.
Super Replenishment: Better watch out, cause your in really furtile lands. Your animals are breeding really fast, cats... cats everywhere. Fish and vermin replenish really fast (although fish dont currently replenish, it would be good to see lakes and rivers full of massive amounts of fish).
Born blessed: Normal creatures being born larger and stronger than normal, making them very very dangerous. Could apply to dwarves as well. They are being born in pristine locations with pure water, the freshest of air, and super crops.
Full of luck: Sometimes your just really lucky in a fight, or the same may be said for the goblins attacking you. Lucky shots that sometimes hit instead of missing, lucky dodges, etc. If toady doesnt like the idea of the areas being lucky, it could just be that with the creature being in such a pristine location, their really at their prime so are able to pull of something special.
All of these are good for your dwarfs, but in the same respect there good for anyone in the region. So its good, but not just good for you