How is it a moral issue? If it's immoral to block certain behavior on sites, then it's just as if not _more_ immoral for users to block ads in the first place. The usual argument is that sites with ads constitute an implicit agreement, etc. If users have the prerogative (regardless of moral ambiguity) to block content they don't like, sites have the same prerogative to block unsavory visitors as they see fit. To say that using FuckAdBlock is forcing anyone to accept content is complete and utter nonsense.
No one is forcing anyone to whitelist the site and view the DRM'd content. The site is simply offering an explicit choice to the user: go away or play by our rules. Whether or not serving the ads in the first place is morally correct simply does not matter—the price for admission could change to require the user's car, their livelihood, their life, and the premise is the same. There's an explicit acknowledgement of the cost and a conscious choice by the user.
An apt analogy would be a magazine on a table with a sign denoting the price. Without FuckAdBlock, the sign reads "Price: ___". Taking the magazine and not paying anything isn't immoral, it just shows you value yourself above others (nothing wrong with that). With FuckAdBlock, the sign now reads "Price: Your kidney". By taking the magazine and not paying, you're quite literally stealing, regardless of the price now on the sign.
No one can force me to watch or click ads either. I can just glue something over my screen – or just mute the sound and watch some other video while an ad is running.
Many people even are okay with watching TV 15min delayed, and instead having their receiver automatically cut away the ad breaks.
You can’t force ads on users.
Now, with the web, we have ads that aren’t just annoying, but actively malicious.
And while I’m the kind of person that often gives people money because they need it – be it because they can’t afford a bus ticket, or whatever – or that I often if I am at a place with a sign "pumpkins 2€" (where you can take yourself, no one watches, etc) still pay more than those 2€.
So it’s not like I actually like doing this.
But advertising is not acceptable. And as long as someone can program computers, I will not see interactive javascript ads. Image ads with a simple image in a link? I even have a whitelist for such ad networks. Seriously.
I'm not arguing that ads are acceptable, merely that it's acceptable for sites and users to come to an agreement where ads must be "unblocked" in order to view content.
Whether it's the publisher's job to inform the users of the risks involved with allowing ads to appear is questionable (should the publisher also inform the user that staring at a monitor for extended periods of time can cause adverse effects, or is this simply common knowledge and implied?).
If you want to discuss the morality of online advertising, that's another story altogether. In my opinion, ads used to benefit the common good at the expense of taxing individuals of time and attention are fine. Take Google for example, the ads they show collectively benefit the public distribution of knowledge (search, maps, books, entertainment, etc.) Just like with any government, if you're unhappy with how taxed resources are managed (or the amount you're taxed), you're free to leave society and live outside of civilization.