So I'm, going to step in here as this isn't actually a lore question. This is a production question and honestly it sits outside of the remit of the lore council to answer. So the on stage answer would not be satisfying.
Ironically the decision previously to not follow the story directly was as a result of player feedback, so we instead went looking at finishing 5th age storylines (Menaphos, which yes isn't finished) and Pieces of Hate, as well as a focus on smaller more comedic quests (Cheesecake, Evil Dave, Back to the Freezer).
As you may have noticed we are moving to a more directed story path. I.e most updates now tie together narratively, rather than every story update being delivered through quests. This will be continuing in future with an internal focus to make sure that as many updates as possible tie into the story in some way.
We always want to do more quests, but the big lavish quests are expensive (time wise) to produce and come at the cost of other possible pieces of content. So we genuinely have to choose between something like a major skill overhaul (Mining and Smithing took us out for a while), a big PVM update or even game improvements. Each update is a carefully weighed choice against the needs of the community and the resources available.
At the start of the year we released The Shadow Reef alongside a less costly quest (curse of the black stone) as a bit of an experiment. Whilst that experiment wasn't perfect (most of that quest was made in devs free time, so lacked the panache of a formal quest) it certainly gave us some food for thought. So I can't give you a solid answer, but there are some good plans in motion that I hope to see bearing fruit soon.
Not terribly exciting or ground breaking I know, but hope it answers the question a bit.
devtrackers.gg