A standard convention on websites, especially corporate-style websites, is to have the logo at or near the top right of the page, and to have that logo be clickable. Indeed, Google still does this on their Analytics homepage, which has yet to receive the black bar branding. http://www.google.com/analytics/
From this perspective, the approach does break convention. And if your reflex action is to expect the logo to be clickable, yes, I think it is a tad annoying.
But it is worth wondering if this convention applies to Google, which is anything but a conventional "website". While Google's scope of influence may once have been primarily in the search engine universe, now the Google universe is much broader: a suite of web-based information tools, of which google.com (the "search" homepage) is just one of many.
With all these disparate tools at your disposal, Google seems to have decided the black navigation bar at the top of all Google-related apps is the best way to access the maze.
If the Google logo were clickable and took you to the Google "search" home page, one could argue that this is actually not helpful from a usability perspective, because you're not really "home", you're only at the "search" homepage. Any time you've entered the Google web universe is when you're "home" from Google's perspective, because you're using just one of the many applications inside the Google wrapper (and the literal wrapper is the black nav bar).
At least that's one perspective on the issue.