The + would have been removed from the Chrome UI because it reduces Google's claim to the "+" mark in their Google+ branding. Google wants people to think "Google+" when they see a button with a + on it (not "create new tab").
I don't see why that would stop them for trying. For instance, search and Google are interchangeable in many discussions. ;)
The above is a bit tongue in cheek. That said, I see where grandparent is coming from. Chrome is Google's web-browser, and these Google+ icons are very often near the top of your browser. I can see how they could come to the conclusion that this could save some confusion. Say, friend calls to help and says "Click the plus sign at the top of your browser"...
Now, I don't think it's a good (or bad) decision. But the fact that I cannot click the logotypes is annoying me to no end.
