Wavelength-routed optical network-on-chip (WRONoC) design consists of topological and physical synthesis. It covers many interacting design aspects such as wavelength assignment, message routing, network construction, component placement, and waveguide routing. Due to the high complexity of the design problem, current manual design usually trades optimality for scalability and feasibility, which results in performance degradation and waste of resources. In this paper, we will present an overview of the existing design automation approaches that have demonstrated their effectiveness in customizing and optimizing application-specific WRONoC designs, and of the potential design automation directions to address a wider range of design challenges. We will also discuss the advantages of comprehensive optimization considering multiple design aspects simultaneously, and the possible barriers that need to be removed to achieve this goal.