I'd say that the recommended HD is probably what Fusion gives you. 
But... modern OSes (certainly Win7 and Ubuntu) should be fine with SATA for virtual HD and CD/DVD.
To explain further: Our recommendations can and do change over time, across products and versions, and sometimes the reason is not obvious – as one example, many users might want to move a VM from the latest Fusion or WS release to an older ESXi release, and we try to avoid having our defaults get in the way of that (as long as the version disparity is not too great), so we might not immediately recommend the best available storage controller for a particular OS in the first release that the controller is supported.
The recommendations also change according to our understanding of the state of the art and the future of physical hardware and guest OSes. All physical Macs have had SATA HDD and DVD for years now, for instance; Now that Fusion has a virtual SATA controller compatible with the AHCI driver in OS X, there's a compelling case to recommend SATA for OS X guests, even at the expense of the aforementioned backward compatibility, since we have a higher degree of confidence that the OS will continue to support AHCI for the foreseeable future. Windows and Linux distros tend to be exposed to a wider variety of (physical) hardware, and have a massive installed base with wide driver support and less likelihood of storage controllers being deprecated, so backward compatibility and proven history are more compelling reasons to keep the status quo.
TL;DR: The default is a generic recommendation, driven by lots of conflicting factors. Adjust to suit your particular needs. Let us know if you think the recommendation is egregiously wrong.
Cheers,
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Darius