It will also make it much harder to see what DNS traffic is occurring
When I was doing front-line stuff one of the things we looked for on a suspect machine was who it was talking to, and logging DNS queries helped, as did logging which IP's they tried to talk to.
Most of the time it was stuff like Win7 getting stuck talking to update servers or AV software innocently (yet annoyingly) using up resources, or other simple harmless oddities. But at times we could see stuff going on that would point us to a bit of malware that had somehow escaped notice or detection, and of course traffic NOT going through our DNS server told us of things amiss.
Thanks Google, yet another tool for security, minor as it may be, now going thanks to your desire to rain more ads on people already saturated.