I've been thinking about this for a while. On the one hand, using the
"or later" clause means we have to place some trust in the Free Software
Foundation. On the other hand, being able to adopt newer versions of the
license without having to contact all contributors is useful for
compatibility (e.g. Apache 2 and GPLv3).
I recently noticed that Section 14 states that new versions of the
license will be "similar in spirit" to the current version. I think this
reduces the amount of trust we need to place in the FSF, as I'd hope
that if a future license did diverge too much from the original spirit
that a court might not consider it valid.
Furthermore, if the FSF went totally crazy, there are many bigger and
more important projects who would experience the same problem.
Graham