|XP is just a number|
Your argument is that you've used a simple, if ultimately unnecessary example, to demonstrate some of the more complex parts of OO; because you didn't want to detract from the techniques you were demonstrating with the detail of the classes you used to demonstrate them.
That is a fine argument.
However, without a convincing example of when it is necessary, (or beneficial in some tangible way), to use the techniques you are demonstrating, it leaves the demonstration looking like a solution looking for a problem.
So, the challenge to you is: show a realistic example of using those techniques that cannot be trivially and beneficially replaced with simpler, non-OO code.
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.