I am well aware of how the steam workshop works.
We won't be doing custom maps on the tactical server for a little while because if we make the server a custom server it won't fill up with players. People are only finding it now because they're using the matchmaking menu and automatically connecting because we are a stock server.
Before we can go off the beaten trail with custom maps, we need to have a regular player base big enough to keep the server populated.
Aside from panj and sinjar (which are just poorly designed maps), I'm actually still getting tons of play-ability out of the stock maps. There's always a new line to learn and optimize.