Chrome is addressing this with a feature that grants access on a temporary basis to the active tab. This is a great improvement for many types of extensions.

http://developer.chrome.com/beta/extensions/activeTab.html

> The activeTab permission gives an extension temporary access to the currently active tab when the user invokes the extension - for example by clicking its browser action. Access to the tab lasts until the tab is navigated or closed.

> The main benefit of the activeTab permission is that it displays no warning message during installation.