Okay, I just wrote a review for the Pinterest app using the Play web site (as opposed to from my phone or tablet) and so far it has NOT posted anything to my Google+ stream.
I always keep G+ open and running in my web browser, so we will see if that changes.
If not, it would seem that (at first glance) the link between having a Google+ account and reviewing apps is just to have a name with the review.
As i understand it, everyone who creates a Gmail account (which you must have to use the Play store on an android device [as we know you don't HAVE to have a Gmail account to use an Android device as long as you are okay with not using certain apps or using the Play store] ) automatically also has a Google+ account.
Unless I am mistaken, then, you don't have to create a Google+ account to leave reviews, you just have to acknowledge that you understand one is being linked to the other.
So if these reviews are not being posted to your Google+ stream, and if everyone with a Gmail account has one by default, then the issue is somewhat moot. You can post reviews with no fear they will end up on your G+ page, and you will never have to actually use Google+ itself for anything else.
In other words, while you are being "forced" to acknowledge that the name linked to your Google+ account will show in your reviews, you are not actually being forced to use Google+. If someone clicks the link to your name in the app review, and you aren't actually using Google+, that user will be taken to an empty G+ page with nothing but your name.
Of course, that may all change if it shows up in my Google+ feed, but in the 5 - 8 minutes or so since I posted the review, nothing has shown up on my G+ feed (which I have been intermittently refreshing while writing this).
EDIT: If you want to test this, any of you who don't use G+, write a review. After submitting the review, click on your name in the review and it will take you to your G+ page. If you aren't actually using G+ for anything, there shouldn't be anything there, not even the review you left.
UPDATE: As of 1:10pm (about 40 minutes since I posted it) the review I left for the Pinterest app still does NOT appear in my G+ feed. So... unless it takes a REALLY long time for it to cross-pollinate (which i doubt), your fears of being "forced" to use Google+ can be assuaged. It looks like you can post app reviews without ever having to actually use Google+. The only difference will be that your real name will appear, and if someone clicks on it, they will see your empty, lonely G+ page.
As of 3:53 it still does not show in my G+ feed so...
TL-DR: App reviews you leave in Google Play will NOT be posted to Google+. You can review apps and never need to use the Google+ account that is created for you automatically whether you like it or not.