Let's take a look at this.
An expansion pack can come out with new rules, concepts, and civs, all for the price of $30. BTS brought 10 new civs and 16 new leaders, many new wonders, graphics changes, rules, ect.
Take a look for yourself at everything in did:
http://forums.civfanatics.com/showthread.php?t=222075
The final price of beyond the sword totaled at $34.99
Now for the DLC. At the current trend each civ is selling for about $5. Ooh! For the price of lunch I can get a DLC. No. You must realize how much you are being ripped off when you purchase DLCs.
If each civilization in BTS cost $5 then the price of beyond the sword from just new civs would be $50. Now you need to add up everything else. Being that individual maps are selling for like $3, its safe to estimate every other thing in the game, if sold as regualr DLC, would add up over $100.
But, sheep consumers don't like to spend that much at a time. So there are two options:
1.) Sell everything combined at a much lower price
2.) Sell everything individually for like $2-5 each
So if you were a developer, you would definitely take option 2 because it equates to lots of money. Previously developers were not quite as capable of doing this, as the games were not internet-based and there was no middle man like steam.
But now that civ v is completely internet based and reliant on steam, the developers can achieve their dreams.
But there is more! This is only the beginning. Soon, they will be selling game necessities as DLC. Half-finished products will be released and then the rest will be sold at high prices. We've already seen this take place for console game. I site Mafia II (also a 2k game!!!!)
A gloomy future lies ahead for gaming.