From the perspective of a casual, though committed, Squeak user, I find value in this approach. It is confusing to identify an object which looks promising to use in an application that is overloaded with use-case specific baggage. #PluggableTextMorph is one example, it seems to be biased towards code composition. I would like to see high-level objects contain the essentials for its purpose with specialized sub-classes providing more application specific additions.
I don't know how this scenario plays out in ObjectOriented architecture, but I think "just enough, but not more" is good guidance for a base class.
As far as taking questionable behavior options to #Preferences, that realm seems to be pretty complicated already.
That being said, I have no objections to any reasonable modifications anyone is willing to invest time and effort in providing ;-) I am providing this feedback because I have been working to develop my skill at writing simple, typical, form (in the fill out the form business sense) style applications, texteditor behavior is something with which I have been wrestling.
- jrm