The same thing that is infecting the film industry.
Amongst the slew of brown garbage, a gem shines forth. Of course, soon the glitter attracts the "me too" designers. They work along the lines of: "That looks like it worked pretty well. I'll do that too and get in on some of the money". Of course, nobody can blame them, because everyone is out to make money.
Then after this stage, comes the dreaded Sequel stage. Where every iota of originality and fun are ground into a fine dust as the designers quest even harder for more cash. I point to game series like Devil May Cry, Leisure Suit Larry, any James Bond game after Goldeneye, just about any game Obsidian has made, Halo, Call of Duty, and Metal of Honor.
Now, I'm not calling every game in these series horrid. As I said, every great once in a while a gem shines forth. But, for the most part, most are the same recycled copy/paste game, just re-released every few months.
I understand that the gaming industry is full of risks, and investors only want to go with something that is safe and makes money.
As I said, this affects the film industry as well.
Can I offer a solution up to help solve it? Possibly not. Otherwise I would be a rather wealthy individual using my money to fight the terrors whatever happened to catch my fancy at the time.
One thing I think would help is: Tone down the Realism a touch. I play a game to relax and have fun. If it's as gritty and realist as everyday life, my imagination doesn't work as well and I do not relax as much. Pretty graphics are nice and all, but most games (note I said most, not all games) have become more about shiny pixels and less about fun and suspension of disbelief.
*climbs down off soapbox, looks around with a confused expression, and wanders off*