Subdividing tiles can be more important than everything else: knowing in which tile a point lies is a fundamental operation for a spatial indexing system and it has to be very easy and efficient.
It's also vital for correct aggregation: if you sum up some quantity over all the subdivisions of some area, you really want that sum to be equal to the quantity in that area. With this hexagonal pseudo-subdivision, it isn't.
I think as long as you're adding the leaves on the same resolution level it should be fine. the problem is when your storing objects in different levels as it would be possible on a KDB tree.
