More comments in the code [what]+[WHY]

Hi
I find this module very usefull, I was studing entities on my own and looking to the same examples you quote.
The thing that I find more difficult is not about understanding what something does but why.
For example: the function model_create() I understand it is intended to create a model but how it is used, because since now I was using entity_create($type, $values), as well as entity_save($type, $entity).
Is model_create() there because is needed by Drupal at somepoint? Is usefull for future development?

I think it would be very usefull for beginner been able to understand why things are that way.