Agreed. I don't see why people think an advertising company would want to make it easy to block ads in their browser.
http://hackademix.net/2009/12/10/why-chrome-has-no-noscript/...
That comment points to a Chromium tracking bug, here:
http://code.google.com/p/chromium/issues/detail?id=16932
It looks like while a developer at Google was working on this project, that developer left Google in October and there's been no replacement.
While this doesn't suggest the feature is the highest priority for Google, it also doesn't suggest Google is deliberately intending to prevent JavaScript or advertising blocking. Sometimes things that didn't get done just didn't get done.
To my last count they currently have 5 ad blocking extensions on Google extensions gallery. One of the is the second most downloaded Chrome Extension.
Generally speaking Google has done so much with Chrome browser in such a short time, I don't mind giving them the benefit of doubt that they didn't get around fixing or implementing the said bug/feature.
On one hand, I'm blocking some of their potential impressions for their lower margin, add-on, commodity product. On the other hand I'm making supply of their higher margin main product more scarce, more valuable. I'm not sure th net effect is too worrying.
Of course this is anecdote but maybe I'm not the only one.
I use Google a lot & I know that I want the ads. For everything else, it's easiest to blanket opt out. Many sites (particularly Israeli news sites which I read sometimes) have ads that bother me a lot.