1. First of all Google is quite busy in major Google algorithm changes that were noticed during the past two months i.e Google Penguin 2.0 and Payday Loan Algorithm. 2. Google wants to refine/redesign their search engine with good results. I mean punishing that sites with fake and poor quality backlinks.
3. Google wants to indicate that Pagerank is not something very funny and easy to get. Its being the money making trend of online backlink builders persons or companies.
4. They need to consolidate their algorithms followed strictly not a money making scheme. Its a true punishment to backlinks seller.
5. Now Google will update their pagerank algo 3 times a year. So all you have to work hard and more to get it. Now its being tough for new blogs to get a PR soon.
Read more: http://www.bloggingways.net/2013/07/know-why-google-has-delayed-pagerank-update-of-july-2013.html#ixzz2axd5sfZO