Booker discussion topic: are departures obsolete?

At the end of a long opinion, which covers a lot of intricate guideline calculation issues, the Seventh Circuit in US v. Arnaout, No. 03-3297 (7th Cir. Dec. 2, 2005) (available here), says again that "the concept of 'departures' has been rendered obsolete in the post-Booker world."  Slip op. at 14.  The Court in Arnaout states, as it did in Johnson in October, that "what is at stake is the reasonableness of the sentence, not the correctness of the 'departures' as measured against pre-Booker decisions that cabined the discretion of sentencing courts to depart from guidelines that were then mandatory."

Given that the US Sentencing Commission has stressed that departures are not obsolete after Booker, and that certain kinds of departures are expressly encouraged and discouraged by the guidelines, I find the Seventh Circuit's obsolescence assertion curious and in tension with its view that a guideline sentence is presumptively reasonable.  The USSC (and Judge Cassell in his Wilson opinion and others) have sensibly argued that the guidelines comply with the mandates of 3553(a) because they incorporate a departure mechanism to allow for flexibility in application.  Is the Seventh Circuit saying that we should throw out all departures (many of which are integrated into particular guidelines), but still consider the rest of the guidelines presumptively reasonable?

I assume that the Seventh Circuit only thinks judicial departures are "rendered obsolete": I doubt the court means to suggest that prosecutors should no longer move for substantial assistance departures under § 5K1.1.  But the sloppy and provocative obsolescence assertion in Johnson and Arnaout would seem to put district courts and practitioners in a tough spot.  Is the Seventh Circuit saying that defense attorneys in Chicago should no longer request a departure based on aberrent behavior under USSG § 5K2.20?  Is it saying that district judges should no longer consider granting departures under USSG § 4A1.3 for inadequate criminal history?

Considering also the Seventh Circuit's sloppy discussion of post-Booker legal standards in Cunningham (discussed here), not to mention the trenchant points made by Judge Carnes of the 11th Circuit (discussed here), I am having more and more doubts about post-Booker appellate review.  I am starting to fear that reasonableness review, by producing and perpetuating doctrinal confusion, may end up increasing rather than decreasing sentencing disparities in the wake of Booker.