One thing I've been coming to terms with- just because something makes no sense long term doesn't mean that it's not a valuable course to pursue short term.
If, and it's a big if, Zynga can reinvent itself in the next 6-9 months, then this initial phase was brilliant in that it gave them the resources they needed to move on to real domination. If they don't reinvent themselves, a few people will have made a lot of money, but nothing permanent will have been built. A real opportunity will have been missed.
But they can't keep on the same path, it just won't work a lot longer.
There are already more complex, deeper games on Facebook, but they are orders of magnitude less popular than these simple Zynga games.
If you go deeper, you go niche.
BTW it's similar for game themes (independently of game mechanics) - more mainstream you go, more potential players you can get.
Just check Facebook games charts. They are dominated by down-to-earth topics - farms, restaurants, aquariums, pets, etc.
Listening to her rant on about it made me realise just how engaging these social games are for younger players. It made me see Disney's acquisition of Club Penguin (http://www.techcrunch.com/2007/08/01/disney-acquires-club-pe...) in an entirely new light.
However, anyone who thinks that Zynga doesn't know all of this is kidding themselves. They saw a temporary situation (novelty of gaming on a hugely growing platform) and attacked it with everything they had. The road will be a lot harder for them in the future, but because of what they did in 2009, they go in with hundreds of millions of users, a strong brand, cheap cost of capital (because they're hot), a ton of cash, and they're probably the only Facebook developer with anything close to leverage on Facebook. They're one of the most aggressive companies out there and they have given no reason to underestimate them.
Also after you've gone through a few of them you seem to get inoculated to the genre.