jsjrodman: They aren't cheaper to make either. In 1980, the cost of 1 programmer and possibly 1 artist, and maybe a little bit of time of some people who write manuals and do box art was far less than the cost of a modern game dev team.
I think the gaming market is more diverse nowadays. You may still have commercial games made by one or couple of people, e.g. indie and/or mobile games.
So it is not like you can't make a relatively successful game nowadays with pretty low investments. But you need a big team and lots of investments, if you want to make a cutting-edge AAA title with Hollywood actors and licensed music. Something that was not made back in the day.
jsjrodman: The obvious thing that changed was the flexible cost that it takes to make each sale (in digital downloads this is far lower than it has ever been before), and the quantity of customers, which is higher than it has ever been before.
Games can also nowadays be sold for a much longer time as you don't need to produce new shipments of physical games all over the world, or care for the limited store shelf space.
Also with digital games there is no second-hand market for games either, which also increases the tail which brings delayed profits. I always considered the retail game prices to include a "second-hand tax", ie. the price took into account that the game may be resold many times. One of the reasons I expect digital games to be cheaper than retail games.
Anyway, considering how GTA V, Minecraft, Clash of Clans and such are breaking the all-time gaming profit records (despite there being nowadays far more competition and fragmentation in the gaming market, e.g. the aforementioned indie and mobile games), I am unable to shed a tear to the hardships of contemporary AAA publishers. Boo hoo, you are making too much money...
Ps. Rather than comparing how much individual games used to cost compared to today (inflation taken into account), I think it is more useful to compare how much people are using money for games total nowadays (per person, and overall). While I am buying mostly cheaper games now than I did in e.g. early 2000s, I am still probably using more money on them than back then. I guess I'm just buying that much more games nowadays, and what is more, I don't buy second-hand games anymore, so all those dineros are going at least partly to the publishers too.
I'm nowadays supporting the game market more than back in the old days.