True but back in the 90's the more expensive games tended to be more expensive because they were either on larger capacity cartridges than usual or featured special add-on chips (SuperFX,etc) which added to the manufacturing cost. I still recall paying around £60-70 for some games on Super Nintendo like Streetfigher 2, Mortal Kombat and Turok on N64 due to the larger than normal capacities.
Game prices fell to around £40 when optical media became the norm in the late 90s and have remained there pretty much since amazingly! Until recently when they started creeping up towards £50. That I could handle. It's this sudden £20 hike to £70 out of the blue which is bothering me and other than pure opportunism I can't really see a reason to justify it.
As I said, and I repeat again, to the end-user, what does it matter whether you get the game on a disc or on a cartridge?
Apart making yourself feel better having more plastic and "tech" in your hand, both still a game, no matter what angle you look at it, what planet you are standing on when you look at it, on earth or on the moon, it won't change the actual function of the object you are holding, a game.
So as a consumer, it makes zero difference the form of physical media that it comes in besides you think you are getting more for your money but in actual function they are identical.
You can tell yourself you are getting "more" but its not like you can turn the cartridge into a microwave after it's done, it has 1 function and 1 function only, being a game, just like a disc.