The idea behind currency is to increase the frequency with which resources move between players and players and between players and ops, not to reduce it.
Brad and turtle shouldn't be removed from the economy, they are an essential part of it! They would be running the only shops on the map which would be guaranteed to have everything "in stock." (Whether they compete or price fix is up to them
) They would in turn be giving out slimeballs to new players and as grants for new projects as they saw fit i.e. slimeballs would replace "hey I'm building X can I have some Y?" requests. It also opens the door for currency based games between players, like my current project. Players could earn money for working on map-wide projects, like community farms/traps, the skyway or the upcoming skyrail.
Also, I feel like bartering items between players is awkward and we don't do it much. Having currency would greatly increase the frequency with which we give each other stuff, because if we have currency, then we can trade our surplusses away when we have them, and not when/if we find out that someone else has something we want.
The way I see it, if we standardize the means through which we all exchange items, we will be more inclined to exchange items. That's what I'm going for, I don't care about simulating a "real economy."