The changes made in CS5 reflect the changed paradigm of the OS and the wishes of the OS vendor with regard to colour management. For that reason, and because that particular paradigm changed several times in a relatively short period of time, Adobe removed the option from CS5 and produced, instead, the aforementioned utility. Dave P. at Adobe quite correctly suggested it would be much easier to maintain the utility in a changing environment than updating PS (also much quicker to respond). Pressure from OS vendors to follow their particular paradigm is significant - they can ask and, if you don't follow, they can force. Better to follow than to have them force the issue and break your app.
Nothing to do with ABW
ABW was never designed for use in a colour managed/ICC workflow
Yes it had shortcomings. Utilities such as QTR Create ICC allowed us to fix that.
- that use was (and remains) effectively a kludge. It's a kludge that works, of course,
It wasn't a workaround but rather an improvement, the missing link in ABW (and any other B&W printing workflow for that matter).
but the changes in CS5 in line with the OS changes removed that option.
Removed what option? One can still print with Printer Manages Colors (just as intended before) and apply a tone transformation within PS (with an ICC profile generated with QTR Create ICC) before sending the file to print. The only difference between now and before is that one used to be able to apply the transform on-the-fly as the file was handed off by PS (with Photoshop Manages Colors) and still retain printer colour management/ABW settings in the driver. Now ABW is only available when Printer Manages Colors. That actually makes sense. So we need to apply the transform before handing the file off. (Just don't save that as your master file.)
that you think happens now, as opposed to before, between a file being handed off with Printer Manages Colors and the Epson driver taking over? Have these changes you believe exist affected printing from CS3 (for example)?
removed was the ability to print a target without any colour management whatsoever (and Adobe, as you say, provided a utility to do so). There are other ways to print targets without colour management - Adobe just had to fix the ability to do so from within the Adobe "empire". But with ABW we always profiled the "colour management" being done by the ABW driver. In other words, we want to profile "Printer Manages Colors".
The only thing that's missing insofar as ABW is concerned is the convenience
to have both Photoshop Manages Colors and Printer Manages Colors operating at the same time when it comes to printing the image.