Why you should add the mod as a dependency rather than just use the shed in the map? There's a few reasons (and these aren't specifically for you, just the way it's "done" afaik).
- If the mod's a dependency, then if it gets updated for a fix or something then the players get the update rather than you then having to update the map to make the same change.
- If it's a dependency you don't need to faff around worrying about crediting and remembering who's objects you used
- It reduces the size of the map
- It means that the original mod author gets new downloads on modhub.