If all you go by is these alerts then you may else well unplug from the internet. They will not keep you safe. OTOH, disabling java will mostly lose animated ads which are worthless anyway. Where this alert utterly fails is that it does not mention that the problem is malicious websites, not java. You must click on (or be redirected to) a malicious web site (and if you are redirected, it means the one you were at was malicious). Going to malicious websites has always been risky and always will be.
Are you retarded?
This is an exploit of the official Java. It has nothing to do with downloading it. You still haven’t read the alert have you?
Nobody uses Java to make animated ads. It's too slow and clunky and too much of a pain to write. Plus, lots of folks have it disabled.
Animated ads are almost always Flash. Although, you can probably expect to see more and more HTML5-based ads.