Lending ebooks is a feature demanded mostly by people who don't pay money for ebooks (and don't pay money for movies, music, or videogames if they can possibly avoid it) and will not be induced to pay money by the feature.
Lending books is part of book culture! I don't own a Kindle yet specifically because half the reason I buy books is to lend or give them to friends. Sharing books is one of the greatest joys of reading. Everyone who shares is not a pirate.
I generally agree with you that people who complain about media costing money are not useful as customers. But there is a world of difference between not wanting to pay and wanting to be able to lend and give what you buy.
Why? Because books can only be lent once. Ever.
This makes the feature almost useless for legitimate consumers, but for non-DRMed files (on the Nook anyways) the lending feature is non-crippled, and (rightly) can occur as many times as the user pleases.
Personally I think it's a load of crap that the lending feature is crippled in such a way, but the fact of the matter is, the only people happy with the existing way lending works are the people who aren't encumbered by it - i.e., the people who never actually deal in purchased/DRMed ebook material.