Hi Steve,
Well again, I respectfully disagree with you here. They do need to know and care. Extrusions and surfaces/polysurfaces are different types of objects that behave differently. Otherwise what’s the point of having them?
I teach people to keep an eye on the Properties panel and the command line to see what type of objects they are selecting or are the result of an operation. Then you get these types of questions:
“Why is the box I just made an extrusion when the person sitting next to me made the same box and it’s a polysurface?”
“Why are the isocurves on my neighbor’s extruded surface different than the ones on mine?”
“Why when I make a closed cylinder directly is it an extrusion, but when I make an open one and cap it to close, it is a polysurface?”
“Why did my extrusion become a surface or polysurface when I cut a hole in it or applied a per-face color?”
How can single-face and multi-face objects both be the same type of object (extrusion)?"
And most importantly:
“Why such a complicated system for simple stuff?”
Putting more patches on the system isn’t going to help understanding it.
And I guess going back to your original premise at the top:
“The user shouldn’t need to know or care.”
If UseExtrusions is turned off by default, that will be true for 99% of users.