At least if you allow them to target you, there's an outside chance that once in a while an ad is exactly what you're looking for.
Imagine watching television, and in each commercial slot, it's the same commercial, all day, all week. I think you would get sick of that commercial very quickly, and after a while, you would begin to have negative thoughts about the company in the commercial.
The same thing happens when my wife watches her Korean dramas online. There was a week or so, that there was this one single Virgin Mobile ad that played before and during every episode, the one that has that scene of the woman giving birth while screaming at her mobile phone. Even though I wasn't watching the dramas, I was close enough to have to hear that ad 25 times over the course of a night, and I began to harbor extremely violent thoughts against Virgin Mobile.
Edit: not sure that answers your question directly actually, but what I really mean is that I would like to see a variety of ads rather than the one or two that seem to be stalking me everywhere and of which I have no interest. I'd certainly rather see ads from more companies of higher quality than mesotheleomia or mortagage financing, but in all honesty, having one or two of those sprinkled in would at least lessen the badgering I get from the few ads I constantly see.
But I do agree that in the past and to this day there are many ads that lack the appropriate context to be retargeting you on ad networks.