>    Eliminating all the intermediate objects gives much less expressive
> code as Tom underlined
>    But providing only naive implementations hides the performance
> problems that users will have to learn sooner or later...

Exactly.

And code expressivity is a dubious criterion IMO: especially in 
Smalltalk, the readability of a specific algorithm can be improved by 
refactoring/renaming its primitive methods, or more simply by commenting 
the non-obvious parts.

Real pedagogical value comes from explaining complex topics clearly, not 
from simplifying them.

Stef