Concept
Existing problems:
I suggest you to take a look at FF XIV and their "Duty Roulette" system.
I would love to see a system in allods where endgame players could also sign up via the queue system like astral dungeons, but then for "lore dungeons" where we can pop in with levelling players. That way we can help them clear dungeons from the questlines (XAES, Oreshek Fortress, Castle Blight, Teps Pyramid, ...), keep it fun and entertained rather than boring and stupid mercs, and we get to relive old dungeons we haven't seen anymore since we levelled away. Oreshek Fortress for example in the League, or XAES in the Empire. You only see those dungeons once per character you level as, and that's it. Why make dungeons for a single-time experience only?

Detailed design
To solve these problems is assumed as follows:
Make the queue system have an extra option where you can tag for Lore Dungeons, and give bonus rewards for endgame players that help levelling players do their dungeons.
Mercenaries are killing the mmorpg feeling, let players step in via this system.
The rewards for levelling players to complete it via the "Lore roulette" could be a bonus for expoints, perhaps double, on all monsters, maybe more droprate on loot, simple incentives for them to do it via that system. Making coop play for an mmorpg rewarding and attractive! For endgame players, perhaps vanity (The real endgame ) ) or atleast some currency we can grind that way to buy vanity from some vendor. Mounts? Shell Skins? there are plenty of content for us to collect but so little ways to gain from.