Except what you pay for with the old World of Warcraft expansions is content that is no longer supported by the developers--that stuff's all obsolete. They are basically charging you money to get to a point to pay for the expansion to play the current content. I would argue that you're basically paying $40 for Mists of Pandaria, while paying another $30 or so for a bunch of stuff you won't want to mess with. I started that game right when Wrath of the Lich King released (well, a few weeks before it), and I never did ANY of the pre-Wrath raiding or dungeons, really. However, I still had to pay for the original game and the first expansion, meaning I basically had to buy 3 games to play the one expansion I was interested in, the current one.
As for cheaper games on consoles, I call crap. Used games have existed for a decade, and prices have just gone up. The gaming industry thrived during the previous generation at $50 for a game. The Wii worked out (initially) with $50 games. They saw a chance at higher profits at $60, and they seized it (much like Microsoft with Xbox LIVE subscriptions). PC games don't offer a used solution, but we've watched several big-name titles hit the $60 mark there as well. It's a simple matter of economics of cost, not something where they HAVE to charge $60 to make up for a used game market older than the prices themselves.