For example, It's probably fair to say that Monsanto is not a constructive part of the marketplace and community, but they sure do have a sustainable profit generating engine.
Edit - if you're going to downvote, how about some discussion as to how this comment does not add to the conversation... since I'm sure there was some other reason for the downvote other than not agreeing with me :)
Just having a business plan and making money should not protect you from criticism or absolve behavior detrimental to the general community! Yes, legally Craigslist has no obligations; that's why nobody's litigating. I argue that morally (at least from a utilitarian standpoint), Craigslist does have an obligation to play nice. And so I welcome critical blog posts and bad publicity.
That being said, in this specific case I think that whether or not there is a moral obligation to let a third party scrape and mix-in your data is very debatable (given that Craigslist does not provide an API).
Sure, people should play nice. And some may interpret playing nice as 'don't scrape other people's stuff for your own startup'. Or at least don't be suprised when they get pissed ;)
In reality, private companies are personality driven.
my 2c