As much as I think it's something well worth thinking about, I'm 100 percent against it due to a number of reasons.
1 - DR trips and age aren't really linked. It doesn't make sense based on the settings as far as I know. A single trip might kill a young person who just isn't experienced enough to handle it, or an older person might have a lifetime experience working with the dark way or be a follower of Dakkru and have had many reasons to go and spend a lot of time there, therefore being more able to navigate their way back out.
2 - Some characters NEED to go to the DR - either for training or for RP purposes.
3 - If you rewrite either of 1 or 2, you invalidate a lot of previous RPs.
4 - The point LigH raised.
5 - If we base age on DR trips, then there's going to be inconsistency based on how often a person plays (same issue if there was a direct age to time played ratio). Several lifetimes worth of game time to one player might pass whereas another person may only log in a few times in that period, or someone might take a break from the game to find they no longer have a reason to play because all the characters their character knew 'aged' and died true death.
6 - True death because a game glitch made me fall through the world x number of times?
7 - True death because I got stuck and /unstick didn't work while there was no GM to move me x number of times?
8 - There would be even fewer people willing to /die for RPs in the DR.
9 - If someone wants to RP as a certain age and to explore that age fully for their character, I feel they should have as long as they wish to do so.
10 - Someone might have spent a really long time planning and building up a long term RP, only to find it can never be finalised or resolved because some of the main players involved aged and died.
11 - Player base would likely suffer for it. Those who level to high levels probably aren't going to want to do that again and, as much as I support PS being a very RP orientated game, I don't think it's good to punish those who invested the time needed to level.
12 - I don't agree that a lack of forced perma-death causes stagnation. People running out of ideas and/or losing interest causes stagnation. Forced perma-death can even cause stagnation in and of itself if the result is that players feel less inclined to invest in a character because they only have x number of lives.
Finally - I make my character's story along with the help of all those I RP with. I want to choose when and if it's her time to die forever. As an RPer and a player I consider myself responsible enough to decide this for myself. If I permanently lost a character I have spent hundreds of hours developing and working with before I feel as though her story is done, I would be leaving PS behind me feeling disheartened, dissatisfied and very disappointed with the game.
(Sorry if this is on the long side or seems at all confrontational. It's not. It's simply an issue I feel quite strongly about. If when I joined PS I had seen that aging was a feature, I never would have joined. If it becomes one, then unless it's avoidable somehow, I believe I won't stay.)