Build your sites for people not the search engines.
It's easy to say that but you have to do a bit of both.
What's the point of having a nice, easy to read, perfect information site if no bu**er finds it?
It's also fine and dandy to say write regular, informative content and people will link to you. That is also not true, in reality how many people are going to link to a website of a local tradesman that they have never seen because it doesn't appear in the search engines.
I agree it would be great it sites ranked on how informative they are, but it's not true.
Take a look at plumbers--manchester/co/uk and tell me that ranks 4th for the terms plumbers manchester based on informative content.
To build a successful site, imo, it is between building for the customer, like fisicx said, and also doing stuff for google, like the site above. One or the other isn't enough.
(That site above isn't mine and I don't think it is a good example of a site at all but it is just to proves that building for search engines does work.)
IMO, outbound links help with SEO - not just user experience.