The address space is daunting in scale as you have noted, but I don't see any lessons learned in address allocation between IPv6 and IPv4. Consider
A lesson learned is that thinking about address allocation is something you do not want to spend too many precious seconds of your life on. That's one reason why the space was designed to be so big. Being penny-wise and pound-foolish doesn't really save you much in the IPv6 address space.
.. address aggregation? .. convergence time?
I'm sorry, but seeing a good fraction of my local IX simply containing a few ISP's deaggregated view of their "local" internal networks versus a sensible allocation policy makes me cry. IPv6 may just make this worse. IPv6 certainly won't make it "better".
Is someone not making sensible use of their IPv6 allocation? Another one of the goals is to enable organization (and the Internet, prior to PI space) to be far more aggregatable. Real example: Instead of one enterprise network having 31 dis-contiguous IPv4 /16s they could get one (large) IPv6 allocation. ... With room to grow and still aggregate. PI space changes that conversation on the DFZ side back to a bit of a swamp until we get that fixed in one fashion or another ... /TJ