I could give you a pretty decent list... For starters, the most creative and risky games are going to be relegated to the indie market. Last gen we had things like Little Big Planet as one of the very few games of this type to be introduced outside of the indie market, this gen, the number of those games is going to be even lower. A lack of diversity in genre is bad for a console.
There is nothing to bring in the casual gamers. With the PS2 there was the DVD player, with the Wii there was motion controls, so what now? Slightly prettier graphics?
I don't know about your families but mine can't even use the PS3 menu system without help... I can use it of course, but don't expect a casual to see Sony's menus as anything but confusing.
For my third weakness, I give you, developers running away. Irrational games is just one of the many studios who don't wanna develop triple A games anymore. Last gen bankrupted a whole lot of developers, and it should only get worse now. Less developers hurts everyone.
