Probably not, as the people who block all ads will likely continue to do so (and who reads ToS anyway?)
But without it, how can you back up any kind of complaint about someone not displaying the ads? There never was any obligation. It's like yelling at someone who leaves their lounge to make a cup of tea during a TV ad break.
I guess it's similar to walking away from the TV. However, DVR providers attempted to use technology to automatically skip ads and there was a huge backlash. The advertisers seem to have won the battle with TV even though you can still fast forward on DVR. Sometimes on-demand doesn't allow it. I still think users are going to win the battle on the web.
