Well basically when they started going into 3d world of gaming is when it all started.
I kind of think the PS1 though still held true for what the older systems like NES, SNES, Sega, and so on had for more difficult games, but it all changed with the PS2.
But yeah, its not like I hate todays games, I was a WOW player for 5-6 years, COD player, like some of the PS3 and Wii titles that is offered.
Although I kind of believe gaming needs to finally go another direction like it did turn of the century.
PS1 did one change- Graphics.
Up until that point, the graphics available were very digital and pixelated...if those are even words. I don't know what terms to use, so bear with me.
Nothing really changed with the PS1 except for graphics- everything else was already there- environment, gameplay, 2 player option, length of gameplay, and saved progress. About the only hardware change was the increase in buttons, but when compared to SNES it's only a small increase.
The biggest changes to gaming came with Simultaneous play and Motion Sensor. You can split Simultaneous play into 4-player cooperative/competitive and Online, but it's all the same, you're only increasing player base and decreasing claustrophobia at best.
Right now, all three gaming systems are trying to push Simultaneous play (PSN, LIVE, Nintendo Wifi) and Motion Sensor (Wiimote, Kinect, Move) before they push single player campaign. Even with something like Call of Duty, Gears of War, Halo, or Super Smash Brothers; it feels as though the campaign is thrown in there for the unlucky few without online capabilities and are rarely stressed as important to the game. The fact that Modern Warfare 3 came out with the Elite Package to enhance multiplayer and get the new multiplayer map packs should be a clear cut case of where their focus is..
In the last few years we've seen an explosion of interest in the independent games scene so I'd disagree heavily with you on that TheRolesWePlay. Most indie games focus on one core game mechanic and explore it thoroughly to grab every ounce of fun that can be had. There are so many interesting titles out there these days with development times of <1 year for $1 - $5. Yes, Game of the Year usually goes to a blockbuster, but 5 years ago it was almost impossible to find the types of games we now see on Steam and to a lesser extent XBLA/PSN.
I'm not ignoring what you said, but rather in my opinion I feel as though the single player games are often forgotten and left out of discussions.
In essence, this is fine, because Video Games for a single player should be just that- for a single player's enjoyment.