Ad pushers have repeatedly shown that they cannot be trusted with our bandwidth and browser resources, they will always try to find the most insidious ways of inserting themselves into our lives, and try to track our every move, no matter how unwelcome they are.
Add to this the long history of malware using ad networks as an attack vector, and you have a very good case for simply blocking everything, in the name of privacy and security.
I hate ads, both for the above mentioned reasons, and because I find them extremely obnoxious (yes, even simple text ads), so I block everything with extreme prejudice. I am also on the "no mailed ads, ever" and the "you will be fined if you ever call this number with advertising" registries. My eyeballs, my attention, my PC, my OS, my browser, my home. Anything I don't trust and don't explicitly allow can just buzz off and leave me alone.