I think we should switch to standard ORDER BY x [DESC] syntax, for several reasons.
First, because ORDER [DESC] is not very readable. By that I mean, you have no idea what it means unless you cross reference with the CF definition.
Second, because it's not a sufficiently better fit than the SQL syntax to justify inventing our own.
Third (and this is the big one) I strongly suspect that we're going to start supporting at least limited run-time ordering in the near future, and this gives us some future proofing while working reasonably well in the meantime: we can simply reject with IRE ORDER BY requests that aren't compatible with the comparator, similarly to what we used to do with unindexed WHERE expressions. (Which is also a good example of us being dragged kicking and screaming into being more flexible at query time...)