Even though Matt Cutts said backlink would become a little less important in SEO, but I myself don't believe that
The question is how Google ranks websites? it relies on content? I'm sure any Seach Engines likes a lovely content. But how can search engines distinguish a good content from another? I don't think search engines are so emotional enough to realize better, exellent or worse content
Search Engines are just a machine, they're not a human, so I think it doesn't have a feeling about content.
In fact, Google owns some instruments, that helps google understand how visitors think about sites. Google Analytics can determine users' behavior on sites. But I think google may not know satisfaction exactly. This is the difference between human reading and Google search engine reading.

What happens if so many sites contain equivalent quality content, equivalent bounce rate, time on site, pageviews...? So what is crucial factor to keyword ranking? that's backlink

Another question! why did Matt Cutts try to lower the role of backlink in SEO? Because he wanted to prevent spammers who are getting spammy and spammy everywhere to get backlinks

I don't think the role of baclink would be lowered, it's always valuable for SEO , no matter how google's algorism changes.

if you need quality backlinks or talk about backlink, pls email me: qualitybacklink4u@gmail.com ; I can provide high PR backlinks to you

I hope you can share your viewpoints to me.