I haven't looked in to this particular instance, but in general...
why buy a company that has no significant revenue? It's not like it's some shock to google - "oh no, meebo doesn't make enough money!?"
So... yeah, the services were provided 'free' in some sense, but meebo was able to continue running before this. Just... yeah.. buy stuff, shut it down.
If it's not a significant source of revenue, it probably doesn't take a significant amount of cash to keep it running for another 6 months to a year.
EDIT: I should have added, I understand the logical reasoning behind buying a company for its assets/talent. Doesn't mean it's not annoying.
I believe Meebo was purchased to become part of Google+ not to be an independently operated subsidiary of Google. This shutting down doesn't mean that Meebo will leave the internet space, it just means that the next time we'll see Meebo it'll be with a "Google+" logo on it.
Larry Page has been shutting down and consolidating divisions of Google for the last 18 months. This appears to fit his strategy at the moment. Why pay for two chat divisions?
They wanted the meebobar only, because it's cheaper than building their own, or it's too entrenched to compete against. Those are the only two plausible explanations that would make sense (to me, obviously) but neither actually make much sense when applied to Google.
> why buy a company that has no significant revenue?
Because users are often just as if not more valuable than the money a company makes. Google probably bought Meebo because they thought the product was a good fit for their new social direction and because it already has a user base.
As far as the services they're shutting down, most of them are in conflict with things Google+ does.
According to CrunchBase Meebo took in about 70 million in investment over the course of the company. They started in 2005 and kept growing so you might guess their burn rate is about a million bucks per month. (LinkedIn lists 160 Meebo employees, so a million might even be way low)
Perhaps 6-12 million dollars is insignificant by your standards, but if they don't have the dough then they have to close up shop. You could argue that they could fire everybody and just keep a skeleton crew to keep the site running for a year, probably much cheaper. But what purpose would that serve for them? It would be a dead company at that point.
Userbase, talent, technology. It's surprisingly easy to have a very well put together company that nevertheless is missing some key elements needed for profitability.
GMail has a pretty obvious source of revenue. But more importantly it's hugely strategically valuable. GMail is the #1 reason for people creating Google accounts. Google has a clear desire to have people signed in when performing searches and it lowers the barrier to adoption for it's other products such as Google Plus, Google Docs, etc.
GMail does make some direct revenue for Google (ads and paid storage), but it was (and probably still is) their #1 method for onboarding users to the Google Accounts system. And that gets them access to pay for all sorts of Google products. GMail has been key in growing Google's active user base.
You can unfortunately no longer log into an AIM account in Gmail and have those contacts appear like in the blog post you linked to. They got rid of that feature a couple years ago.
The entire IM client UI was one big ad. I'd be surprised if they couldn't make enough money to run the IM client by plastering a giant Best Buy elf across the screen, especially given that eBuddy makes its money in the same way.
If you were paying them and they were making a profit then you might have a better chance.