Currently, there are no plans to add temporary legendaries, as stated
in this 2018 stream, but since legendaries are supposed to be limited/unique, I worry that they might disappear completely from the server if those accounts stop playing (or get banned). Or even worse: they might go back on that decision and we end up seeing multiple warriors all equipping the same legendary
"unique" sword

So I was wondering if there could be temporary legendaries, that disappear after a certain time. As rewards for things like:
- Being the mayor or defender of a node and getting some special item that can be used only to defend the node. Like Anduin casting that epic heal (reward/city);
- Defeating a rare monster that spawns in a random cave in the world and drops some legendary item (luck/exploration);
- When forging a normal sword, having a chance of forging a legendary sword (luck/profession);
- being in the top PVPers of the server (reward/pvp) not sure about this one, since it would buff pvpers that are already winning;
- Guild that performs better than other guilds in some way (reward/pve);
So instead of giving every player a legendary item, it could be restricted as a reward for
only a handful of best and/or lucky players. Then, after a set period of time the item disappears [insert eventual cooldown] and can drop again
This way legendary items are kept as rare, special rewards, and could even have higher stats without turning the whole server into an episode of Dragonball Z. At the same time, it would give more players/guilds/nodes the chance of having their time in the spotlight. Otherwise it could just become a race to be the first to get the item, and everyone that joins the game later is excluded permanently, making players want to abandon old servers and restart on new ones constantly.
As a bonus: this could even end up reducing account trading for real money, since an account with a temporary Scarab Lord Mount (WoW example) would not be worth as much. And I don't know about you, but seeing players running around with Legendary items that they didn't earn, just because they purchased them for real money... that really grinds my gears.

How do others feel about something like that? Do you think it would make the game more epic and more balanced (stronger Leg. items, but restricted to fewer players) or do you think it would ruin legendaries (if it is temporary, it makes no sense to even try to get it)?
Sources:
Wiki: Legendary Items