There are technical problems with amplification attacks. I expect up to 30Gbps. https://lists.dns-oarc.net/pipermail/dns-operations/2009-December/004673.htm...
Don't know where you get your numbers from, but I have not seen more than 50 pre-fetch queries starting up Chrome normally with 6-8 tabs (after a mach reboot), of which ~30 are queries for "Google properties" like groups.google.com.
And there are serve privacy issues in conjuntion with Chrome. Chrome prefetches the FQDN for those links, the mouse is hovered on. This way Google is able to trace how a user works with a web page. Of course, if Chrome would record the user actions directly and send them to home, everybody will cry loud.
You really need an extra large tin hat. As you may know the implementation is open source and available to any other software vendors to do the same and other folks to actually see the code to determine what it does and what it does not. Also as Google stated on the public announcement while on the temporary logs they have your IP address on the permanent logs they don't keep any personally identifiable information. (http://code.google.com/speed/public-dns/privacy.html) Even with the IP address if you are behind NAT or a firewall, as you mentioned Google has to expect on dns-ops, the same source IP address may be used for dozens or hundreds of users and Google has no way to know who is doing which query. I'm sure that sooner or later Google will figure how to take advantage and monetize whatever statistics they collect, and they are extremely smart and good doing so. A big difference between Google and what some ISPs have been doing to put more coins in the coffer is that Google is a very dynamic, smart and interesting company driven by long term vision not short term greed. The real message and political implications from this community should be: "Stop screwing up with the DNS". My .02 Jorge