I've had similar thoughts, albeit only for Google's sites. I would imagine this would be something more likely to be seen through Chrome (or even the Chromium OS).

My gut reaction is that most people wouldn't want Google on top of every other site they visit. Of course, I'm also amazed at how many toolbars I have seen people install and run concurrently in IE, so I could easily be wrong.

Personally I disagree. Maybe as options, but not by default. The bar looks nice because of its simplicity.

Adding a bunch of addon attachments would ruin the unobtrusive functional aesthetic that i think that google is going for.