Design is a series of transformations turning the abstract into reality, and it can be complex. A mixture of ideas based on design principles, a clients brief, planning restrictions, budgets, and design time frames. These sometimes conflicting requirements can divert the natural course of the process.
A concept design allows you to focus on one idea without distraction or diversion, and therefore fully develop the initial design. However, do not think that the result is purely theoretical, as conceptual designs provide a source of inspiration and motivation for the more " complex" and real designs.