Also, all GPs have added B/B objects before. So builders have never been left out of packs.
This pack is simply adding a mechanic where now the Sims essentially acknowledge that there is a B/B mode. This is the difference for when people are saying that they already do what their Sims will now be able to do with this pack. Simmers have always been able to renovate homes and community lots. In previous GPs, what is new to the player is also new to the Sim. Now it is just new to the Sim, which I think is a distinction worth noting.