Backlink is needed are important factor in search engine algorithm and relevant backlinks are good source to get quality traffic also.
Simple, if you are looking for Ranking in Search Engine and especially in Google you need quality back-links that points your website. More the quality back-links high the PR of your website. And if you are able to get natural back-links, say suppose if someone share your blog as user is impressed than this be considered as quality natural back-links.