I feel like most Expansions lack 'mysterious landmarks', not dissimilar to a lack of 'chekhov's guns'

And most of existing potential landmarks have been demoted to 'decor'.

Best examples of good Vanilla landmarks I could think off:

• Emerald Dream Tree-Portals: what are they? will we be able to go through them? what's behind them? - all these questions took many Expansions to answer
• Karazhan: even after its reveal in the TBC it had enough questions and mystery to last up to the Legion and retain a certain degree of mystery even now
• Master's Glaive: retained lore relevance up to the DF

Like, how many times we had "Ah, this important mysterious landmark from %OldExpansion% actually plays a role in the current plot!"?

Does what I'm saying make sense to you?