Merge some servers!
Transfer to a high pop server…. Its not that difficult….
Relax. They are working on a better LFG tool, and hopefully it solves this problem. It might come out soon, with the oct. 22nd content update.
The problem most likely isn’t the amount of players on the server, but your LFG for Story mode. Many people are level 80 and have run them once or just don’t want to run them on alts due to the ability for higher levels to zone in them to explorables (which actually have rewards).
One other solution is to make Story mode more worthwhile for people to revisit. Perhaps award a small amount of Dungeon tokens for beating the Story mode like, say, 10 – 20. This should be easy enough to apply retroactively too; simply give anybody who has the Explore mode unlocked the appropriate number of tokens for that dungeon.