There's definitely a lack of self-reflection in selling scammy ringtone offers and weight loss, but sneering at ebooks as being "unethical". But that's just human nature.
I probably miss out on a lot of AM profit because I don't personally want to sell stuff like that - I just couldn't look at myself in the mirror with any sort of pride having spent a day flogging pink patches to teenage girls.
On the other hand, I sell an expensive eBook which is bloody excellent and delivers a lot of value to the people who buy it. Enough that they often come back and buy a coaching course for several $K. However it's aimed at a demographic who really need the information (NOT Internet marketers).
As to why it's an ebook, and not a published book - simple. profit. If I sell an ebook from my site for $50, it makes $48 (after paypal fees).
If the book is published in paper form, you have to pay for typesetting, printing, storage, distribution, shipping and possibly retail. That leaves anywhere between $3-8 profit for the author. (add another 10% if you sell it through an amazon affiliate link. W00t.)
Add to the fact that you can get an ebook written, hit "print to PDF" and have a saleable product within 10 mins, versus weeks for a paper book, it's a very attractive format.
That said I agree that all make money fast ebooks are a total scam, and those who hawk them should be tarred and feathered and run out of WF on a rail.