Just something I noticed checking the game files. I found the file that has the chance of stats increasing or decreasing based on age, and there's one interesting observation. Every race has an age where they start to decline, one where they decline further and can no longer gain vitality (around the max age the game allows at creation), and an age where their decline gets even worse (vitality *always* goes down at level up at this point).

..,.except Elves. Elves never decline. As long as an elf is not below the minimum starting age, stats will only have a 15% chance of dropping at level up, while they will increase 50 or 60 % of the time. So, don't worry about your elves getting old, and your Kiss of the Goddess traps can be saved for other races.

Some other observations:
* Fairies, from age 5 to 30, get better stat growth than other races. So, while they have a rather short life span, at least they get good stat growth during their brief life.
* Each race has an age, usually the starting race, below which their stat growth is rather poor, with stats frequently going down. For Devilish, this happens until age 50, so you might want to have them intentionally trip Treasure Chest traps until them (and don't be afraid to let them die and revive them; they'll age 1 year as a side effect, but in this case you want that).
* Magic Dolls are an exception to the above rules, but they're one of the 3 unused races (leftovers from other games in the series). They still suffer at old age, however.

If a party member is not gaining any vitality at all, no matter how much you r4load, and you know their vitality is not maxed out, it's time to retire that character. Or, find a way to lower their age (say, by duplicating age reducing items). Or, find a way to change their race (there's one spot you can do this in the final dungeon, though apparently a PC version specific bug will crash the game if you're in windowed mode when that happens).