She points out that the First Warden isn't interested in the arling per se, but that having a Warden ruling over a domain creates an interesting precedent for the order, which can now be regarded as important even when a Blight is not afoot.
This section contains spoilers for: Dragon Age: Origins - Awakening.
Mistress Woolsey insists that the Warden-Commander should secure the Pilgrim's Path, the road between Amaranthine and Denerim - which will enable trade to flow again - because a large portion of the defeated darkspawn horde moved north from Denerim and the Arling is in a severe humanitarian and economic crisis. After this conversation the quest Trade Must Flow is activated. In addition, she asks the Warden-Commander to convince itinerant merchants to sell their goods at Vigil's Keep.