One note: the $3 I noted in the article actually isn't CPM, it's Cost-Per-Reach, or Cost Per Unique Impression. This is an important distinction because most digital/display advertising functions on a CPM basis, where one person might see an ad multiple times. On Facebook, when a Page promotes a post, that post is only displayed to that user once.
Brands have a tendency to abuse the trust of someone opting-in, whether that's on Twitter, Facebook, Email, etc. When this happens, most people aren't aware enough to understand the cause and effect - instead of blaming the brand for being spammy, they get frustrated with Facebook.
The News Feed Algorithm and Sponsored Stories are Facebook's way of ensuring a better user experience. By pushing brands to pay a small price for distribution, Facebook gets brands to think about what they're publishing and to take advantage of the targeting options that Facebook makes available, so that their content reaches the right people.
One thing to note, when you said "my personal feeling is that if I follow a brand it's because I want to see their updates", the tricky think about facebook is that you don't "follow" a brand like you do on Twitter, you just "like" them. In my opinion, it's a small but important distinction. Just because you enjoy a certain brand doesn't mean you actually want to know every little thing they're doing.
This allows me, as a Facebook user, to complete my profile and declare that I like something, even if the marketing that the associated Page is doing isn't something I want to see.
This ensures that profile information remains accurate, which is critical for ad targeting - people don't start unliking things they actually like, just to avoid annoying marketing. The interest graph remains intact even when brands make poor marketing decisions.
Maybe I've been on the other side for too long, but I equate liking a page with opting into their facebook marketing content, and I unlike if I want to opt out.
I'm not sure why anyone would assume a very casual social "hey I like X" is equivalent to "subscribe".
In normal social circles there an expectation that the you want to hear about things you 'like'. For instance if in real life I have a friend who 'likes' classical music then when I hear something about classical music I will talk to them about it.
Also like is not like subscribe because the idea behind subscribing is that you receive everything. For instance if I 'subscribed' to a magazine I would be rather upset if they only sent me every 7th issue, or only sent me issues when the newspaper had not arrived.
People commonly associate/link their personal identity with media and products, certainly.
Twitter is more obvious semantically, but heavy Likers of brands on Facebook already understand the implication, and increasingly so will everyone else, regardless of the terminology. For me it's basically to the point where I only Like things that are owned or run by people that I actually know.
I never liked anything on facebook (via a 'like' button) but I do have several likes.
Before the facebook feed , before even the facebook wall, the personal information field of your profile was a text blob. Over time facebook parsed this information and matched it to pages, giving me likes.
Now i get updates from films in my feed because 7 years ago I added them to a text field called 'movies/tv'
Doesn't bother me because I hardly use facebook anymore. But it is interesting to think how it has changed.
I'm sure that Mark Cuban's hockey team drives a lot of viewers to watch TV. Does that mean Mark should get to advertise for free on television? That's not how the networks see it. [edit: this is a really bad example]
It's funny that we've gone from being outraged about spam and all-pervasive advertising, to being outraged that spammers have to actually pay to send the stuff.
The reason it feels like such a terrible deal here is that you aren't paying $3 CPM to reach a new audience, you are paying $3 CPM to reach your audience. Sure, Facebook can argue "it's the most targeted audience possible, they're Mavericks fans!" but the counter to that is "of course they are, it's my brand that put this audience together".
Brands use Facebook because it's far more user-friendly than trying to collect your fans together on your own website, and therefore it's a better solution - easier for your fans means more will do it, so you have more people to market to. However the comparison is that they're people who have chosen to subscribe to you, and therefore the pricing comparison is not to digital advertising, but to writing to fans on a website, or a blog, or through email newsletters. This is why it feels like, and arguably is, a rip off.
As to the argument that it's needed from a user's point of view and that Facebook happens to be able to monetise to help their users (e.g. jeffwidman's comment: http://news.ycombinator.com/item?id=4785852) I'm not really sure. It's probably a valid point. I'm not a Facebook user myself (but my marketing work occasionally covers Facebook), my personal feeling is that if I follow a brand it's because I want to see their updates. All of their updates. In my head, it's the same as signing up to a newsletter, or subscribing to an RSS feed, just through a convenient third party. But as I don't do it myself, I'm happy to consider myself wrong, or in the minority, maybe if I was an active user following many brands that I care about I would find that getting 100% of their messages would ruin my Facebook experience.