Did your service offer a paid API? Scraping happens because of a lack of better options. Surely you can understand why the scrapers didn't want to contact you beforehand.
If you're using my data to hijack my traffic, without asking, you could have all the right justifications in the world but you're still a prick. Who knows, maybe your orphanage building app will move me tears once I hear about it and I'll give you free access.
EDIT - I can't reply to your comment below, but FWIW I agree that scraping sites in this manner is unethical. I am merely describing the logic that most scrapers go through for self justification and legal protection.
But whatever. It just saddens me that the internet is a constant "don't be a dick" battle with companies like the scraper guys.
(edit - understood :) )
Incidentally, I'll be shopping later. May I give you $5 for you to drive to London and take me there? I was going to steal your car, but then I figured I'd be a good citizen and demand you provide it to me at your own, prohibitive, loss.