> But if essentially any SMW-based extension can get added, then I don't see what the big benefit is.
> have symbolic links to the right version/tag/branch of each extension
> But perhaps I'm missing something in this whole thing.
I think so - if you go back to my initial list of advantaged you'll see that they are not all obtained with the Semantic Bundle approach (or having links to git tags, which is essentially the same).
> at the very least, it would take a lot of time and coordination
Yes, it forces the maintainers of the extensions to manage their code properly or have it end up being disabled by default (if it was not already) and tagged as unstable/unmaintained/foobar. Having things work will not be more difficult then it's now, people will just be more incentivezed to have their code working with the latest SMW release. If you consider that everything is released together, it's actually easier for maintainers to have their stuff working property due to much simpler compatibility requirements.
> And even if you accomplish that, there are still other extensions, like Validator
> and Maps, that would require coordinating outside of the SMW repository.