Unfortunately, preventing those events from running code could be easily programmed around, if, as I assume you mean, you let the rest of javascript run as normal. If you're trying to run code in response to someone clicking on link A but the browser had disabled onclick for link A, you could still register an onclick for the entire page and in that listener examine the coordinates of the mouse to see if it's over link A and then run code "in response" to the click. This is just one of countless ways you could get around the rule I'm sure.

Maybe the browser itself should have more efficient anti-clickjacking tech, such as blacklists and spam classifiers. Users should be able to block all popups from a specific site when protection doesn't work well automatically.