I too have this problem -- but tonight someone in a Google+ Hangout explained a few things to me about how Google+ "decides" which contacts to sync with your android phone.
This answer is either completely missing the boat, in which case, sorry for wasting your time -- or it may explain a few things. He said it's all tied to your Google+ Account settings (on the website) and which circles of yours are designated as part of "Your Circles" or not.
On the web, not phone: Go to your Google plus page(s), click the Settings icon under the notifications area > select SETTINGS > (you arrive at your ACCOUNTS page, with Google+ highlighted) > Scroll down this page past Google+ games, to "YOUR CIRCLES" > Click CUSTOMIZE > "Customize Your Circles" . Here is a checkmark list of all of your circles.
My helper in my Hangout session explained: "Any of the circles that are checked are also included in a superset called "YOUR CIRCLES", and any contact within "YOUR CIRCLES" gets synced to your Android Gmail contacts.
He explained: "When you un-check the box, that circle will still function as a specific group for those individuals inside it, but they will no longer be included within the special category called "YOUR CIRCLES.""
He said "The people and circles that ARE within "Your Circles" are the people you want a slightly-higher relationship with -- receive notifications from them, or you want to be able to chat with them. Thus, Google presumes you also want to be able to send and receive email from them (!). These are the people that will sync to your Gmail account on your phone, because you're designating them as being "more special" than just a circle.
He said "Your Circles" is confusing nomenclature, and it would be helpful here to really think of "Your Circles" as "Your Outer Circles" or Outbound Circles -- because those are the ones that are pushed to your phone.
The downside, of course, is that we all want to be able to have notifications from certain groups of people whose interests we share, but it doesn't mean we want to email them. According to my Hangout "helper" , to get rid of all those Google+ people showing up on your phone, you have to unselect the checkboxes within this "YOUR CIRCLES" Settings area.
If they are checked, then within google+ you will receive notifications from them, and you can chat with them etc, and they will appear as contacts on your phone.
If they are unchecked, then within google+ you will NOT be able to receive notifications from these people, etc., but they will not be added as contacts to your Gmail on your phone.
Hope that helps. If this turns out to be wrong or incomplete, please correct it. Thx