Why Google Make Google Plus +1 Button:
They make this because they want if visitor see any quality content then he click on that button to inform search engine that this is a quality content.SO as we know that the habit of search engines that it always send traffic to quality content.
Is Google +1 Button Can Get Higher Ranks In Serp:
One of my friend ask me that question befor 2 months then i say him we need to experiment for that.So both of us submit a post after 3 days that article was on 7th page of the google searches.So we decide to see the impact of Plus 1 button then we give that post link to our all friend who were on google plus and say the please plus 1 this post.WE got 31 +1 and after 3 days we see that article was on google 1st page on 7th rank.So then my that friend get how it is positive for higher ranks in serp.
Try this article it will boost your site traffic +1 this post if you like.