Leaving aside discussion of 'real life' for the moment (a dull place, best avoided) :
I think there is a question of game-play balance needs resolving in the longer game-worlds : inevitably, desirable new models, whether with improved range, capacity or fuel-efficiency, do not follow neat 15yr cycles of introduction : neither does players expansion and re-fleeting needs : also, once the initial rush of players settles down after a decade or so, the number of new players coming into the used market drops awfully, and stays low : its BK/restart mainly who pretty much soak back up the planes they lost on the BK : well established players dont really need the used market, they can finance new builds, so for them, its for opportunistic buys or short-term cover during re-fleets/expansions.
from my experience broking, the initial decade of an aircrafts life-cycle is not an issue : its when it gets into the 10+yrs it gets troublesome : expensive heavy maints while waiting for a buyer eat away at the soul : I've c-checked some hulls numerous times before they went, or d-checked early just to get rid of the '1.6yrs to d-check' sales-killer tag off them. Alternative is to write them off after 10 yrs then let them rot until the 15yr scrap button shows up
So, the question then is, in the long-game worlds, what exactly is the used market/brokers for? I'd suggest that, once the initial game phase is over, its primary purpose, in-game, should be to keep the production wheels turning by taking unwanted aircraft off players hands, releasing some equity and allowing them to finance the re-fleet to newer models : if they cant do that we will end up with a log-jam of unwanted aircraft and, worse, a paucity of new orders for many types which will then compound further expansion problems by letting production lapse and thus load new-build demand even further onto the favoured few types.
Taking this problem with other requests for parking fees, and it becomes a recipe for a stagnant market, no-one will consider an aircraft with a 10 yr life-span until replacement with a better model : its make your initial choice then sit and wait 15 yrs and hope a better replacement is still around then : unless you are a mega-carrier awash with the green stuff, but thats not all of us.
PS : as an illustration : I've just BK-ed my JA8 airline : it was profitable, very, it never had to borrow a cent : owned all its aircraft, had as many again out leased : issue was I couldnt face a re-fleet/upgrade of the operational side as moving on just a pair of that type had taken years, never mind adding 25 to the market : okay, Pipers are not the most popular : but my new airline will run Embraer and upgrade within that range : so much for experimentation with new types : back to the old faithfuls and doing things the same way as before, yet again : annual production line closure panics included.