**Edit**: As of August 2016, it is no longer required to have a Google Plus Profile to leave a comment in Google Play Store.  
  
However, it would have great sacrifices to comment anonymously in Google Play Store as you have to [remove your Google+ Profile](http://plus.google.com/downgrade) and as long as you create one again, all your 'previously anonymous' comments will immediately be linked back to your new G+ profile.  

Note: The following text is obsolete. Refer to above.  

> <S>Due to Google's requirement since November 2012, a Google+ profile is **required** to leave comments under contents from Google Play Store, as is discussed [here](/q/86166). All those comments from anonymous users without a Google+ Profile are left before Nov, '12.</S>