I look at this as a really healthy thing for advertiser ethics.
The growing popularity of ad-blocking software is tied directly to the proliferation of horrible advertising methods.
There have been 3 sites I work with directly that have tried taking on annoying advertising campaigns and witnessed their regular repeat users flock to ad-blocking software as a result.
Heck I've seen ad-blocking change the face of online fax. It used to be that everyone was signing up for faxing services to spam out a promotion. My fax affiliate sites were very active, but almost exactly one month after I saw my email fax services, (starting with metrohispeed.com) establish effective anti-spam filters, the fax affilliate sites started losing volume.
I've witnessed a top review site (faqsaboutfax.com) launch 5 different free trial programs all at the same time just putter along as if there was nothing special at all on the site. This is the sort of promotion that would have caused a completely synthetic spike in the traffic a year ago and now, thanks to ad-blockers, it's barely registered an increase in traffic!
So yes, they do hurt the sites with bad activity, and they have a direct impact on other sectors, but in general it's an improvement over the horible ads we were seeing from the various low-brow "test your IQ" and "how many eyes does this girl have" types of advertisers.