>> You can already add an expression column that shows and allows editing the Rating field value in a numerical form* and remove the standard Rating column from the view.
Thank you for the suggestion. I'll try working with it. Of course, as a half-way workaround, it creates a different behavior inconsistency. For a "no stars" entry it shows "? stars" instead of the logical value 0, even though entering "0" results in no stars displayed and an expression value of "? stars". Also, it doesn't provide a pick-list of acceptable values, so anything but 0 to 5 results in "? stars". And (minor) a decimal value is truncated to the integer.
A custom field would provide total control, but be disconnected from the built-in Rating stars display in the Tag dialog.
>> there is no way to hide or protect the star ratings in AW > Tag.
That's not too bad. I've unintentionally changed the Rating there, but not often enough to declare it's a problem.
However, given the sophistication of MC in many other areas, it seems out of character to display a set of stars so prominently as if it trumps everything else about a track. I bet most MC users categorize music and control their smartlists via several field values, with Rating being just one parameter. A variety of fields might merit prominent display in a particular user's categorization scheme (another discussion about whether text display formatting could be field/column-level).
The big risk of the Stars system is in views, where even a single track's Rating can be changed inadvertently, because it's common to click columns to select and edit values, safely because the first click just selects the row, and a double-click enables editing -- except for Rating, the only value that is CHANGED INSTANTLY by the first click.
I see a problem with UI inconsistency -- one field out of all that changes with just a single click seems an unnecessary deviation. Is the assumption that users are constantly changing the Rating value, much more often than any other value? If not, why make it so different and "easy" to change this one field?
Your suggestion and my suggestion would both be huge improvements, providing user control over the field's behavior. Simply allow the field to be viewed and clicked as Stars, OR allow it to be shown and edited as integers 0 - 5, thereby behaving like every other field.