Since both the design and construction of your project are handled by one company there is greater accountability for all aspects of the remodeling project. A third party can confuse issues. With one company managing the entire process from start to finish, the overall remodeling experience runs more smoothly.
If design and construction are managed by separate companies finger pointing can occur when things go wrong on a remodeling project. This often results in the homeowner picking up the tab for increased construction costs due to errors or omissions made by the designer, architect, or contractor. But, when the designer and the remodeler are in the same company, there is a shared responsibility. The designer has more motivation to address all the details of construction rather than just leave it for the builder to deal with.