Why this PR3 Site with Good MoZRank and PageSpeed Score is NOT getting any Search Traffic?

I have started a Motivational Quotes website (http://www.thequotes.net/) around 2 years back, and added lot of features like Facebook cover app, AutoTweet app, Motivational Calendar Generator, Gallery, etc. apart from adding lot of Motivational Quotes in both Text and Image format. But this site is NOT getting any search Traffic. It is really very strange. I had confirmed with Google that there is No manual spam action for this site. MozRank is also good comparing to other similar sites which are getting good search traffic. I tested it with Google PageSpeed, and the score is good. It is having Google PageRank Also (PR 3). I couldn't understand why it is not appearing in Search Results. Even I tried Disavow Tool to ask Google for removing suspected backlinks
I understand that it is having duplicate content as the Motivational Quotes are available in lot of other sites. But it may not be issue. Because, the all top ranking sites are also having duplicate content. I Anyway, I am making sure that I am collecting the Quotes in unique way, though the individual quotes may be duplicate of wiki quotes or any other quotes sites.
I tested the entire site for broken links, and there is no broken link there. And, I set this wordpress-based site with all SEO related plugins (WP Super Cache, All-in-One SEO pack, XML Site Map generator)
I never use any black-hat SEO approaches intentionally.
Is there any other way to check/find the reason for this issue?