It’s totally feasible to achieve different looks by playing with the color scheme. (Blood/Void Elves anyone?)
Next to that, a Night Elf settlement should always include trees (and a lot of vines, lol) in ways you’d never see in Suramar.
Sure, there are gardens in Suramar, but they are just parks where nature is ‘caged’, whereas in Darnassus and also on the shore of Feralas (Feathermoon Stronghold!) there are tree homes.
For the Night Elves it’s a matter of just visually integrating nature and the settlement.
Also while the Nightborne buildings look new or very well maintained despite of their age, the Temple of the Moon in Darnassus was ancient-looking (due to the vines?) even though not old at all, as Teldrassil itself was grown after the Third War afaik (year 20-21?).
So imho having the Night Elves draw construction materials to build a new settlement from the ancient ruins scattered across Kalimdor totally works.
And that makes Feralas a very good spot due to both the thick forest and Eldre’Thalas.