There is a reason why living objects may choose fractal structure. It might simply be a conservation of
genetic material (
DNA, and the subsequent synthesis of
protein). If you have separate genes that specify growth of a
tree's
trunk, its main
branches, its smaller branches, the sticks that come off of those, the
twigs that come off of those .. etc, you start to get into a mess. How many genes should be made and how do you control them all?
For trees, adopting a single physical rule of bifurcation at certain points reduces the control complexity of the system, while allowing for significant variation and adaptability of form.
Natural objects such as snowflakes and river systems also take on fractal shapes because the physical laws that define their shapes work on many different size scales. Of course, all bets are off once one gets down to molecular and atomic scales, where physical laws themselves are changing.