Adobe never had plans to compete in the DAW market. When they bought Cool Edit and hired its creator, it was to fill a hole in their video-centric product suite. This version sees better integration with Adobe Premier, potentially better integration with DAWS (Pro Tools and Logic being the target market) and Mac compatibility. The latter makes the most sense from a business standpoint since Adobe has always been a Mac-oriented company (you won't find many PCs in the Adobe offices!).
So while this will disappoint many who use Audition as their primary DAW, it won't affect the majority of AA users who use it primarily for editing. I've been looking forward to the next release for a while, but sadly it seems to have nothing of interest to me. I have a copy of Premier but it crashed the two systems I tried it on and was clumsy to use compared to friendlier applications such as Sony Vegas.
Adobe's explanation for why the new version lacks many AA3 features was weak, and strangely reminiscent of Cakewalk's logic regarding X1:
Adobe Audition CS5.5. is a completely new product. It offers many of the core capabilities in Adobe Audition 3, but because it is based on new underlying technology, it does not have an identical feature set. Some features, such as MIDI support, are not included because other tools on the market offer those capabilities, and they are not part of the core audio post-production workflows at which Adobe Audition excels. Other features, like CD burning, are not included because the majority of newly created content is distributed digitally, and inexpensive or free third-party CD burning tools, such as iTunes, are readily available.
"...
because other tools on the market offer those capabilities"?? WTF? Since when does a software vendor justify dropping functionality because competitors also do it? That's usually a justification for putting the feature IN!
The bottom line is: keep on using AA3 if you already have it, otherwise grab a copy of Audition 3 now while you still can. If any online vendors are unloading AA3 at a discount, jump on it.
EDIT: a more frank explanation (presumably by an Adobe employee) appeared in a forum posting:
The reason that not everything is in the new version is simply because there wasn't time to do it all properly. The developers have had their fingers burned with releasing 'unready' versions of Audition before (AA2.0) because of corporate release strategy, so this time, they've played safe by making damn sure that the bits that are there work properly.