I used to be completely paranoid about vandals using page moves to shuffle article titles, by repeatedly swapping titles via a temporary page. That is, until I realised this attack was already protected against, using the feature you describe above.
A feature, hmm...
This has already happened several times, we've seen this scenario played out to the fullest extent. We've implemented a few features to deal with it, such as "undo" links in RC and checks for "newbies" attempting to move pages. Allowing users to move over arbitrary redirects would open us up to truly irreversible attacks, rather than just attacks reversible only by admins.
What you mean by irreversible you mean that the page jumps over arbitrary redirects and you can't just click "undo" to reverse them all? Hmm... that would be a problem.
(aside) Excepting the fact that redirects (usually) are pretty straightforward when it comes correlations (but still, it's not as convenient as UNDO.
I'm not sure anymore. Page moves are such an arcane matter and most Wikipedians wouldn't know what to do about page move weirdness. Then again, after really looking at the system, I'm starting to think that the way page moves is implemented is genius: a mix between giving the users control and keeping the situation under control.
And Brion, err, sorry, I sorta tried out my theory on the Volapuk article and forgot to clean up my mess. :oops: I added a little extra documentation on this feature on the Metawiki page on Page Moves.