We are currently living in a very exciting time where the various complex processes that can affect galactic disk formation and evolution are being uncovered and studied observationally and theoretically. Combined with the now well established cold dark matter structure formation scenario the time seems ripe for self-consistent models of galaxy formation with predictive power. Given the high capacities of present-day supercomputers it is understandable that one tries to including as many processes as possible, most of which being however not well understood. These models not only suffer from a large number of free parameters. They also do not necessarily lead to insight as they are so complex and depend on so many different implemented physical aspects that it is impossible to clearly understand what in the end the origin of a certain result will be.
I wonder whether one needs a high complexity in order to understand important questions of galactic disk evolution, like the two KS laws, the origin of turbulence in the diffuse interstellar medium or in molecular clouds or the origin of the strong correlation between the viscous timescale and the star formation timescale.
Let us try to solve simple questions first before we focus on the complex puzzles that involve many processes that are not well understood yet.