MG Siegler makes a good point in his latest post on PandoDaily:

Google’s real problem with Search+ isn’t actually evilness nor greed nor antitrust — it’s something much bigger: relevancy.

Even before Google started manually inserting G+ content into search results I found myself logging out of my account when searching in Google, or using the Incognito window, because I wanted to find the most relevant link in my search results period. Not just the most reverent based on what Google thought I was looking for, based on my location, my search history or whatever else they started collecting over the years and ranking my results based on the assumption they “knew me”.

If I search for something and Hans across the room searches for the same thing, relevancy means that we both find the same results.

Which somehow challenges the notion of Google and demands more static content, rather then the fluidity of whatever Google was going for. If I want fluidity I choose Facebook or Twitter. Constant changing content, answers and responses.