> I still contend that this is not a "centralized vs. distributed" issue, then, but really a matter of linear vs. non-linear history, and branch management between releases.
Agreed I guess, except you conveniently omit the huge influence that a centralized system has on branching policies (the "workflow").
> Certainly the "centralized repo" tools that I'm familiar with have gained better branch and merge support over the years,
As long a system is centralized, you will neither be able to permanently erase branches nor to re-organize the past in any way. And you will need some human-level protocol to avoid collisions. These, and probably others reasons I miss will always have a chilling effect on branching. Why do you think git-svn is so popular?
I am pretty sure that the main reason why most decentralized systems were invented is because their authors wanted to increase the branching and merging freedom.
My point here is that the tool has a huge influence on the way it is used. Sure you can often hammer down a nail with a screwdriver, but do people do that routinely?