The answers often vary, we didn't have such a fevered pitch of console wars back in the day. Today we have 3 companies competing for the top spot, the 360 and PS3 fighting for best gaming/entertainment console and the Wii striking a whole new category of gamers. Way back when it was only Nintendo doing the heavy lifting, eventually Sega came with it but could never do more than put a dent into consoles like the SNES and N64. Then Sony stepped up to the plate and dropped heavy hitters like the PS1 and PS2. 

But I feel one undiscovered reason for why games don't feel or play the same, and that comes to the developers. 

Now I have some of the greatest respect for what developers do, my current plan is to actually become one. They work the hardest and get little show for more than credits we all skip through at the end of a game.

But with respect, like a lot of things, you must earn it. A long time ago I remember a developer being asked why he made a particular game and his response was pretty simple, it was the game he wanted to play. And that really seems to be the key, these guys and girls are gamers themselves, so wouldn't they have a lot of insight on what makes a game awesome? So I would encourage all developing companies to make the games they want, not what might sell units.

The evidence is everywhere that games are no longer made for fun. Remember when every game was 1-4 players? (within reason of course) Well no more, even games with co-op can only be played with someone online, a feeble attempt for more game units to be sold. A cheap cop out if you ask me. Games should be focused on the fun aspect, not the technical aspect, not about features, but about fun. I ask myself that everytime I look for a new game, does this look fun? And thats what developers should start asking, is this fun? Not will this sell?