There are other (quite simple) plugins to stop any malware from running (like noscript, etc) while at the same time, not having an adblocker even installed. The two are not mutually inclusive. Thus, it isn't ridiculous in the least. It's actually ridiculous to imply that if you have one, you must have the other.
More importantly, these days, you only find malware ads (consistently) on real shady sites. When it makes it to big reputable sites, it actually makes the news because of how rare it has been. There are dozens of other ways to get malware (software downloads, etc) but you don't see people ceasing to download anything off the entire internet, they take a risk because they want the product. The risk is virtually identical -- it depends on where you go and what you do.
> Ads are being used to distribute malware through reputable sites
Sure, that has happened. But it's rare and again, it makes the news when it happens because of how rare it is. You make it sound like reddit.com, facebook.com or news.google.com serves up malware every other day. That just isn't the case. Not even close.