I liked the quests bastion had. It was a reason to visit spawn daily, as well as detracting from the grindy feeling of leveling.
On the way to the exchange (if you want one) you could have town shops and limit the amount of towns on the map to the number of shops available. Get rid of small shops in the trade district, to encourage people to join towns and contribute. If you want a small shop make one in the wilds with a personal region. With town purchased shops, you wouldnt need towns to generate currency through anything other than their town shops. If possible allow for town shops to tax each personal shop depositing the money taxed into the town bank.
An alternative way to get people to traverse the spawn would be to offer currency for more than just souls/gold, a baker could purchase bread, cake, pies..., a fisherman could offer currency for fish caught, alchemist potions, librarian books so on and so forth. Instead of an exchange, the spawn could offer many different means of gaining currency in different locations of the spawn. Coupled with daily quests, i feel this would make the spawn more lively, help against map decay, and keep spawn bustling. I see no issue with letting a new player sit in spawn fishing so they can sell it to the fish merchant to save for an lwc. That time they will be reading chat and hopefully learn some of the ins and outs of herocraft.